My app charges customers but does not handle sales tax or VAT. Set up automatic tax calculation using my payment provider's tax tooling (Stripe Tax if I use Stripe, or the equivalent for my provider). 1. Enable and configure: turn on automatic tax in the provider dashboard, register my business's tax jurisdictions, and set my default product tax code (digital goods/SaaS, not physical goods). 2. Checkout integration: update my checkout/payment flow so the provider calculates tax automatically at purchase time based on the customer's location. Collect the billing address fields the provider needs for that calculation. 3. Subscriptions: make sure recurring charges also apply automatic tax, including how the provider handles a customer's address changing mid-subscription. 4. Display: show tax as a separate line item in my checkout summary and on receipts/invoices, so customers see subtotal, tax, and total rather than a surprise number. 5. Records: make sure the tax amount per transaction is stored or retrievable for reporting, since I will need it when filing in each jurisdiction. Do not try to calculate tax myself with hardcoded rates; rates and rules change constantly and vary by jurisdiction. Do not change my prices; decide with me whether prices are tax-inclusive or tax-exclusive and make it consistent. Give me: the configuration steps for the provider dashboard, the code changes for checkout and subscriptions, and a test using the provider's test mode to verify tax appears for customers in different regions.