See perlfaq4: "Does Perl have a round() function? What about ceil() and floor()? Trig functions?" In particular, take a look at the ceil function in POSIX.
If you tested that you might be surprised at what it actually does. I'll give you a hint: what does if ( !$var eq '00' )really mean? (See perlop and look at the table of precedence...)
You might also want to specify how negative numbers should be rounded. If -12345 should round to -12300, my solution will work but the approach you outlined will produce different results.