diff --git a/poi/src/test/java/org/apache/poi/ss/formula/atp/TestMRound.java b/poi/src/test/java/org/apache/poi/ss/formula/atp/TestMRound.java
index 9df86af58a..da3e67e4be 100644
--- a/poi/src/test/java/org/apache/poi/ss/formula/atp/TestMRound.java
+++ b/poi/src/test/java/org/apache/poi/ss/formula/atp/TestMRound.java
@@ -20,12 +20,11 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import org.apache.poi.hssf.usermodel.HSSFWorkbook;
 import org.apache.poi.ss.formula.eval.ErrorEval;
-import org.apache.poi.ss.usermodel.Cell;
-import org.apache.poi.ss.usermodel.FormulaEvaluator;
-import org.apache.poi.ss.usermodel.Sheet;
-import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.ss.usermodel.*;
 import org.junit.jupiter.api.Test;
 
+import java.io.IOException;
+
 /**
  * Testcase for 'Analysis Toolpak' function MROUND()
  */
@@ -39,42 +38,76 @@ class TestMRound {
         =MROUND(5, -2)  Returns an error, because -2 and 5 have different signs (#NUM!)     *
      */
     @Test
-    void testEvaluate(){
-        Workbook wb = new HSSFWorkbook();
-        Sheet sh = wb.createSheet();
-        Cell cell1 = sh.createRow(0).createCell(0);
-        cell1.setCellFormula("MROUND(10, 3)");
-        Cell cell2 = sh.createRow(0).createCell(0);
-        cell2.setCellFormula("MROUND(-10, -3)");
-        Cell cell3 = sh.createRow(0).createCell(0);
-        cell3.setCellFormula("MROUND(1.3, 0.2)");
-        Cell cell4 = sh.createRow(0).createCell(0);
-        cell4.setCellFormula("MROUND(5, -2)");
-        Cell cell5 = sh.createRow(0).createCell(0);
-        cell5.setCellFormula("MROUND(5, 0)");
-        Cell cell6 = sh.createRow(0).createCell(0);
-        cell6.setCellFormula("MROUND(0.79*7.5, 0.05)");
+    void testEvaluate() throws IOException {
+        try (Workbook wb = new HSSFWorkbook()) {
+            Sheet sh = wb.createSheet();
+            Cell cell1 = sh.createRow(0).createCell(0);
+            cell1.setCellFormula("MROUND(10, 3)");
+            Cell cell2 = sh.createRow(0).createCell(0);
+            cell2.setCellFormula("MROUND(-10, -3)");
+            Cell cell3 = sh.createRow(0).createCell(0);
+            cell3.setCellFormula("MROUND(1.3, 0.2)");
+            Cell cell4 = sh.createRow(0).createCell(0);
+            cell4.setCellFormula("MROUND(5, -2)");
+            Cell cell5 = sh.createRow(0).createCell(0);
+            cell5.setCellFormula("MROUND(5, 0)");
+            Cell cell6 = sh.createRow(0).createCell(0);
+            cell6.setCellFormula("MROUND(0.79*7.5, 0.05)");
 
-        double accuracy = 1E-9;
+            double accuracy = 1E-9;
 
-        FormulaEvaluator evaluator = wb.getCreationHelper().createFormulaEvaluator();
+            FormulaEvaluator evaluator = wb.getCreationHelper().createFormulaEvaluator();
 
-        assertEquals(9.0, evaluator.evaluate(cell1).getNumberValue(), accuracy,
-                     "Rounds 10 to a nearest multiple of 3 (9)");
+            assertEquals(9.0, evaluator.evaluate(cell1).getNumberValue(), accuracy,
+                    "Rounds 10 to a nearest multiple of 3 (9)");
 
-        assertEquals(-9.0, evaluator.evaluate(cell2).getNumberValue(), accuracy,
-                     "Rounds -10 to a nearest multiple of -3 (-9)");
+            assertEquals(-9.0, evaluator.evaluate(cell2).getNumberValue(), accuracy,
+                    "Rounds -10 to a nearest multiple of -3 (-9)");
 
-        assertEquals(1.4, evaluator.evaluate(cell3).getNumberValue(), accuracy,
-                     "Rounds 1.3 to a nearest multiple of 0.2 (1.4)");
+            assertEquals(1.4, evaluator.evaluate(cell3).getNumberValue(), accuracy,
+                    "Rounds 1.3 to a nearest multiple of 0.2 (1.4)");
 
-        assertEquals(ErrorEval.NUM_ERROR.getErrorCode(), evaluator.evaluate(cell4).getErrorValue(),
-                     "Returns an error, because -2 and 5 have different signs (#NUM!)");
+            assertEquals(ErrorEval.NUM_ERROR.getErrorCode(), evaluator.evaluate(cell4).getErrorValue(),
+                    "Returns an error, because -2 and 5 have different signs (#NUM!)");
 
-        assertEquals(0.0, evaluator.evaluate(cell5).getNumberValue(), 0,
-                     "Returns 0 because the multiple is 0");
+            assertEquals(0.0, evaluator.evaluate(cell5).getNumberValue(), 0,
+                    "Returns 0 because the multiple is 0");
 
-        assertEquals(5.95, evaluator.evaluate(cell6).getNumberValue(), 0,
-                "Rounds 5.925 to a nearest multiple of 0.05 (5.95)");
+            assertEquals(5.95, evaluator.evaluate(cell6).getNumberValue(), 0,
+                    "Rounds 5.925 to a nearest multiple of 0.05 (5.95)");
+        }
+    }
+
+    @Test
+    void testBug66189() throws IOException {
+        try (Workbook wb = new HSSFWorkbook()) {
+            Sheet sh = wb.createSheet();
+            Row row0 = sh.createRow(0);
+            Cell a1 = row0.createCell(0);
+            a1.setCellValue(5);
+            Cell c1 = row0.createCell(2);
+            c1.setCellFormula("(A2+(B2-A2)*A1/10)-1");
+            Cell d1 = row0.createCell(3);
+            d1.setCellFormula("ROUND(C1 * 100, 2)");
+            Row row1 = sh.createRow(1);
+            Cell a2 = row1.createCell(0);
+            a2.setCellFormula("(A3-1)*0.63+1");
+            Cell b2 = row1.createCell(1);
+            b2.setCellFormula("(B3-1)*0.5+1");
+            Row row2 = sh.createRow(2);
+            Cell a3 = row2.createCell(0);
+            a3.setCellValue(1.35);
+            Cell b3 = row2.createCell(1);
+            b3.setCellValue(1.35);
+
+            double accuracy = 1E-9;
+
+            FormulaEvaluator evaluator = wb.getCreationHelper().createFormulaEvaluator();
+
+            assertEquals(0.19775, evaluator.evaluate(c1).getNumberValue(), accuracy);
+            assertEquals(19.78, evaluator.evaluate(d1).getNumberValue(), accuracy);
+            d1.setCellFormula("MROUND(C1 * 100, 2)");
+            assertEquals(19.78, evaluator.evaluate(d1).getNumberValue(), accuracy);
+        }
     }
 }