I'm adding my 2 cents about rounding and versions of perl, as it seems you have your solution but didn't mention your perl version. If you're running Perl 5.6.X verses something greater than 5.8; you'll find that the math(rounding) may be different. This was certainly true for sprintf and rounding between 5.6 and 5.8 (See Perl5.8 delta: Understanding of numbers).