Index: poi/src/main/java/org/apache/poi/ss/formula/atp/MRound.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/poi/src/main/java/org/apache/poi/ss/formula/atp/MRound.java b/poi/src/main/java/org/apache/poi/ss/formula/atp/MRound.java
--- a/poi/src/main/java/org/apache/poi/ss/formula/atp/MRound.java	(revision d280b7438854dd9aaa31d723559303358548946a)
+++ b/poi/src/main/java/org/apache/poi/ss/formula/atp/MRound.java	(date 1651231121300)
@@ -17,6 +17,9 @@
 
 package org.apache.poi.ss.formula.atp;
 
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+
 import org.apache.poi.ss.formula.OperationEvaluationContext;
 import org.apache.poi.ss.formula.eval.*;
 import org.apache.poi.ss.formula.functions.FreeRefFunction;
@@ -56,7 +59,9 @@
                     // Returns #NUM! because the number and the multiple have different signs
                     throw new EvaluationException(ErrorEval.NUM_ERROR);
                 }
-                result = multiple * Math.round( number / multiple );
+                BigDecimal bdMultiple = BigDecimal.valueOf(multiple);
+                result = bdMultiple.multiply(BigDecimal.valueOf(number).divide(bdMultiple, 0, RoundingMode.HALF_UP))
+                        .doubleValue();
             }
             NumericFunction.checkValue(result);
             return new NumberEval(result);
Index: poi/src/test/java/org/apache/poi/ss/formula/atp/TestMRound.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
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
--- a/poi/src/test/java/org/apache/poi/ss/formula/atp/TestMRound.java	(revision d280b7438854dd9aaa31d723559303358548946a)
+++ b/poi/src/test/java/org/apache/poi/ss/formula/atp/TestMRound.java	(date 1651231006183)
@@ -51,6 +51,8 @@
         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;
 
@@ -70,5 +72,8 @@
 
         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)");
     }
 }