[ic] Discount to subtotal

[Thomas N. Stefanidis]

How can i make a discount like this?
from 20.000 till 49.999  5%
from 50.000 till  99.999 10%
form 100.000 from 249.999 12%
form 250.000 and over  15%

I have found this code but i don't know how to change it with my values
:

[discount ENTIRE_ORDER]
                  $original = $s;
                 $f =($s);
                 if ($s <= 2499.99) {
                 $discounted = $s * .93;
                 } elsif ($s <= 4999.99) {
                 $discounted = $f * .88;
                 } elsif ($s <= 9999.99) {
                 $discounted = $f * .83;
                 } elsif ($s <= 19999.99) {
                 $discounted = $f * .81;
                 } elsif ($s >= 20000.00) {
                 $discounted = $f * .78;
                 }
                 $difference = $original - $discounted;
                 return $discounted;
[/discount]