add a bit to a number before rounding to combatx machine rounding error

Author: Alex-Jordan

macros/core/PGauxiliaryFunctions.pl

@@ -175,12 +175,16 @@ =head2 Round
 
     Round(1.789,2) returns 1.79
 
+Before rounding, the environment variable numZeroLevelTolDefault is added to a number (or subtracted
+from a number if that number is negative). This is done to combat machine rounding error where
+somthing like 1.5 has become 1.4999999999999997.
+
 =cut
 
-# Round contributed bt Mark Schmitt 3-6-03
 sub Round {
-	if    (@_ == 1) { $_[0] > 0 ? int $_[0] + 0.5                      : int $_[0] - 0.5 }
-	elsif (@_ == 2) { $_[0] > 0 ? Round($_[0] * 10**$_[1]) / 10**$_[1] : Round($_[0] * 10**$_[1]) / 10**$_[1] }
+	my $x = $_[0] > 0 ? $_[0] + $envir{numZeroLevelTolDefault} : $_[0] - $envir{numZeroLevelTolDefault};
+	if    (@_ == 1) { $x > 0 ? int $x + 0.5                      : int $x - 0.5 }
+	elsif (@_ == 2) { $x > 0 ? Round($x * 10**$_[1]) / 10**$_[1] : Round($x * 10**$_[1]) / 10**$_[1] }
 }
 
 =head2 lcm