Oliver POS loads the WooCommerce Tax Tables, and applies Tax Rates based on your Shop Address. Oliver POS looks at the Country code and the State code to match the base shop address with the tax table.

If you have a Pro Plan, you can also apply custom tax rates by clicking on the tax section at the checkout. Multiple Tax Rates can also be selected at once for custom compounding tax.

If you're in the US or another place with short vs. long ZIP codes, make sure you use the short one (five digit code), e.g. 12345 instead of the long one (ZIP+4) 12345-1234.