use Math::BigFloat to properly round your number, then printf with work correctly. 
#!/usr/bin/perl
use warnings;
use strict;

use Math::BigFloat;

my $num = Math::BigFloat->new("-0.000004");
$num->bfround(5);
printf "%f\n", $num;

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

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