To add sales tax to all invoices, navigate to the Settings.
Select Invoicing from the billing section of the left navigation menu
Toggle on Sales tax and enter a rate.
Assign custom sale tax rates to a customer's invoices.
Do you do business in multiple cities with different sales tax rates? You can override the global sales tax rate on a customer by customer basis.
Navigate to the customer's profile.
Select "Payment" from the Billing section of the customer profile menu.
Toggle on the sales tax override and add a custom rate.