Hello. I need to add a discount for items purchased to my shopping cart.
This would be something like
1-3 for $10.00 each
4-6 for $7.50 each
7-10 for $5.00 each
11-13 for $2.50 each

Just a note w.r.t. the answers. I didn't do the install of osCommerce so a version upgrade would be the more difficult solution (however neccessary if need be). I do have the power to modify the php, I just need to know where.

Thanks in advance.