Does perl have a round function? What about ceil() and floor()? Trig functions?

For rounding to a certain number of digits, sprintf or printf is usually the easiest route.

The POSIX module (part of the standard perl distribution) implements ceil, floor, and a number of other mathematical and trigonometric functions.

The Math::Complex module (part of the standard perl distribution) defines a number of mathematical functions that can also work on real numbers. It's not as efficient as the POSIX library, but the POSIX library can't work with complex numbers.

Rounding in financial applications can have serious implications, and the rounding method used should be specified precisely. In these cases, it probably pays not to trust whichever system rounding is being used by Perl, but to instead implement the rounding function you need yourself.