Fix ROUNDUP and ROUNDDOWN for floating-point rounding error (#1404)

Closes #1404

CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 - Fix active cell when freeze pane is used [#1323](https://github.com/PHPOffice/PhpSpreadsheet/pull/1323)
 - Fix XLSX file loading with autofilter containing '$' [#1326](https://github.com/PHPOffice/PhpSpreadsheet/pull/1326)
 - PHPDoc - Use `@return $this` for fluent methods [#1362](https://github.com/PHPOffice/PhpSpreadsheet/pull/1362)
+- Fix ROUNDUP and ROUNDDOWN for floating-point rounding error [#1404](https://github.com/PHPOffice/PhpSpreadsheet/pull/1404)
 
 ## [1.10.1] - 2019-12-02
 

src/PhpSpreadsheet/Calculation/MathTrig.php

@@ -1064,12 +1064,13 @@ class MathTrig
         $digits = Functions::flattenSingleValue($digits);
 
         if ((is_numeric($number)) && (is_numeric($digits))) {
-            $significance = pow(10, (int) $digits);
             if ($number < 0.0) {
+                $significance = pow(10, (int) $digits);
+
                 return floor($number * $significance) / $significance;
             }
 
-            return ceil($number * $significance) / $significance;
+            return round($number + 0.5 * pow(0.1, $digits), $digits, PHP_ROUND_HALF_DOWN);
         }
 
         return Functions::VALUE();
@@ -1091,12 +1092,13 @@ class MathTrig
         $digits = Functions::flattenSingleValue($digits);
 
         if ((is_numeric($number)) && (is_numeric($digits))) {
-            $significance = pow(10, (int) $digits);
             if ($number < 0.0) {
+                $significance = pow(10, (int) $digits);
+
                 return ceil($number * $significance) / $significance;
             }
 
-            return floor($number * $significance) / $significance;
+            return round($number - 0.5 * pow(0.1, $digits), $digits, PHP_ROUND_HALF_UP);
         }
 
         return Functions::VALUE();

tests/data/Calculation/MathTrig/ROUNDDOWN.php

@@ -61,6 +61,16 @@ return [
         31415.92654,
         -1,
     ],
+    [
+        4.44,
+        4.4400,
+        2,
+    ],
+    [
+        5.20,
+        2.26 + 2.94,
+        2,
+    ],
     [
         '#VALUE!',
         'ABC',

tests/data/Calculation/MathTrig/ROUNDUP.php

@@ -61,6 +61,16 @@ return [
         31415.92654,
         -1,
     ],
+    [
+        4.44,
+        4.4400,
+        2,
+    ],
+    [
+        5.20,
+        2.26 + 2.94,
+        2,
+    ],
     [
         '#VALUE!',
         'ABC',