I feel like I shouldn't have to ask this, but how do I apply a category discount? I think I've read through all of the relevant documentation, but I don't see any explicit instruction about how to apply the discount to the cart.
Quantity discounts can be applied in two ways: specific to a product, or specific to a category (or categories). If a discount is added to the cart with a product, then the quantity discount will apply to that product and that product only. This is often desired for items that may be ordered in bulk, like screws or other hardware. If a discount is set at the category level, the discount will apply across all the products in the category equally, so category-based discounts work best when the category contains similarly priced items.
It seems pretty clear that I can add a product discount as a parameter in the add-to-cart form on my site, but it's totally unclear how I add a category discount. Can someone give me a nudge in the right direction?