Try ceil in the POSIX module:

use POSIX qw(ceil);
print ceil (15/2);
[download]

For positive numbers int(15/2) + 1 probably also works, but the docs for int discourage this use.

Update: Actually, int(15/2) + 1 will not work very well at all, because int(14/2)+1 also produces 8, whereas you want 7 (I guess). Sorry to have brought it up...