I looking to see what my options are. I know this field doesn’t exist on the create terminal. But I do see it in orders and an order is created. But I am not able to update the order I assume because its already been paid. Is there an option for tax and if not is this something in the future
Currently, there isn’t a way to add a tax to an order from a payment created with the Terminal API. This is a very popular feature request and we hope to have more for you soon. 
We’ve just released 
Terminal API beta features including order itemization on the Terminal which includes taxes, delayed capture to authorize a payment upfront and collect funds later, card on file for recurring purchases, and app fees so you can monetize on payments processed via Terminal API. Learn more . 