Check https://www.avalara.com/ https://www.avalara.com/. You give them a list of products and/or services, the location of the buyer, and they tell you the taxa

Check https://www.avalara.com/ https://www.avalara.com/. You give them a list of products and/or services, the location of the buyer, and they tell you the taxable amounts for each item. It's all via API so can be built into your cart and checkout easily.