Quantity Discounts

I am trying to set up a site to sell tutorial DVDs. We have 6 different DVDs and I want to offer a discount for multiple purchase. So say if they but 3 or move DVD there is 10% discount. I cant figure out how to do it checking the forums there is some suggestions to hack the php... argh! Can you help.

j15.mickturns.com/index.php/micks-products-hika

You can do that by creating a coupon with a category restriction and the "include sub categories" option turned on and the "Coupon percentage applies to product only" turned on and the "Minimum number of products" option set to 3. Coupons can be created via the menu System->Discounts.

Thanks Nicolas... I am having trouble finding those parameters... are they only in the commercial version?

Under Discounts I can create a percentage coupon but no where can I find "include sub categories" or "Coupon percentage applies to product only" or "Minimum number of products"

They are indeed only in the commercial editions.