POS Product Taxes configuration is as easy as ABC. First configuration will be in Point of Sale > Configuration > Point of Sale. Select a POS that will use the new POS product taxes. Then enable the Use POS Product Tax. Finally, set the product prices if you want to display as tax-excluded or tax-included prices.

Second configuration will be in Point of Sale > Products > Products. Update the POS Customer Taxes (in General Information tab) and POS Vendor Taxes (in Purchase tab) fields for all products available in POS.