I've always gone for:

use POSIX;
sub round { floor($_[0] + 0.5) }
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I've always wondered why Perl doesn't include a round function, it is something that tends to stump beginners. I also wondered if this was faster than japhy's code.

Benchmark: timing 100000 iterations of round1, round2...
    round1: 65 wallclock secs (64.59 usr +  0.00 sys = 64.59 CPU) @ 15
+48.23/s (n=100000)
    round2: 47 wallclock secs (47.78 usr +  0.00 sys = 47.78 CPU) @ 20
+92.93/s (n=100000)
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And it seems to be slightly faster. I think it would also be marginally more understandable from a maintanace standpoint.

Also remember that if you work with floating point numbers you might get things you don't expect, for example, adding 0.01 to 0 99 times gives you 0.990000000000001.

The module Math::FixedPrecision seems promising, but unfortunatly it rounds 0.50 to 0 rather than 1.

use Math::FixedPrecision;
for (my $i = Math::FixedPrecision->new(0); $i <= 1; $i += 0.01) {
    print $i, "\t", Math::FixedPrecision->new($i + 0.01, 0), "\n";
}
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I know I've gone off on a slight tangent here.. but is there some nicer way to deal with this. I haven't used Math::Currency but that does look promising.

gav^