Setting up shipping rates for products and digital goods
I'm trying to figure out what would be the best way to accomplish this. I have a products table that has a foreign key named idcategory_product that pertains to what type of product or category the product belongs to. The categories are greeting cards, audio cds, and audio downloads. When these products apply to the cart their shipping rate is a flat rate that changes based off of the quantity of items in the cart. My problem is when a digital good is purchased it still adds to the quantity in the cart and could therefore change the shipping rate. How can I set the cart up to know that when a digital good is being purchased there shouldn't be a charge for shipping or that it shouldn't be applied to the quantity in the cart?
I need a little push in the right direction.