Here in Ontario Canada and in several other provinces , they have a tax called  the HST, which is a combination of two taxes - provincial and federal. I have created a zone for this tax and added the HST provinces to it. Some products (I have hundreds of them) are exempt from the provincial portion of the tax and only pay the federal portion. I am assigning those products to a  product category call PST exempt and created a zone specific tax exemption rule for that category to remove the HST from those products. Now I have to add back only the 5% federal tax. This can be done on each product individually, but I have hundreds of products. Is there a way to tax by product category instead? Better yet is there a way to reduce the tax on some products by a certain percent (using -8% didn't seem to work)?