Greetings all,
I can't remember now where I found this but it was from someone here... very helpful.
Thanks whoever it was.
I Hope this helps.

sub add_commas {
  my $text = reverse $_[0];
  $text =~ s/(\d\d\d)(?=\d)(?!\d*\.)/$1,/g;
  return scalar reverse $text;
}
[download]

-injunjoel
Update:
It's tachyon's code!
Thanks tachyon!
Always give credit where credit is due. (original post:352970)