If you need to round a number in Perl you can use the POSIX method round(). If for some reason you don't want to use the POSIX method I wrote a pure Perl version of round() that is pretty fast.

use POSIX;

my $num = 3.14156;

print(POSIX::round($num)); # 3
print(round($num));        # 3

sub round {
    my $num = shift();
    my $ret;

    if ($num < 0) {
        $ret = int($num - 0.5);
    } else {
        $ret = int($num + 0.5);
    }

    return $ret;
}

Along with round, sometimes you want "round to the nearest X", which I also implemented:

sub nearest {
    my ($nearest, $num) = @_;

    my $div = $num / $nearest;
    my $ret = round($div) * $nearest;

    return $ret;
}

Note: Math::Round also includes both of these functions.