I have products (needles) in a category. Some of them are sold in packs of 100 and some in packs of 500. The quantity of needles in the box is set as a product attribute. I want to apply cart rules based on the total number of needles in the cart. F.x. 10% if you buy 1000-2000 needles, regardless of the combination of 500/100-packs. Don´t think it can be done with the vanilla Magento (CE 188.8.131.52) and haven´t found any module for it. I have tried the Magento forum, but no luck there. Could someone point me in the right direction?