I would love to read what you mean by "sprintf does not really 'round' from a mathematical point of view". I have observed that sprintf will round up from the number right outside of the requested precision. For example, from my perspective, the following list when rounded to 5 decimal places should end in 70 (i.e. 1.777695 rounds to 1.77770), do note that it *does not* always work that way. 
@nums= (
    1.777695,
    1.77769501,
    1.667695,
    1.66769501,
    1.557695,
    1.55769501,
    1.000695,
        1.00069500001,
    1.000696
    );
foreach (@nums)
{
    print sprintf "%7.5f\n", $_;
}

[download]
Output on Perl 5.6.1: note: it usually rounds if the next significant digit is 5 or greater 
1.77770
1.77770
1.66769
1.66770
1.55770
1.55770
1.00069
1.00070
1.00070
Output on Perl 5.8.5: note: it usually rounds if the next significant digit is 5 or greater 
1.77770
1.77770
1.66770
1.66770
1.55770
1.55770
1.00069
1.00070
1.00070
Given the example, I would love for you to elaborate on your sprintf opinion.

In reply to Re^2: Negative zero? There's gotta be a sprintf that undoes that, right? by rgiskard
in thread Negative zero? There's gotta be a sprintf that undoes that, right? by rgiskard

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