Some How-To links that get and keep you going with using Auto Tax in Xero, using Avalara.
Avalara "Auto Tax" is native inside Xero if you have sales tax needs when doing business in USA. Here's some "How-To" links that get and keep you going with using it. Hope it helps!
Use auto sales tax in invoices
State-by-state guide to the taxability of digital products
Economic nexus: Find out where you’re on the hook to collect and file sales tax