In Channels Settings, Taxes are setup by default to use Match on Tax Code Name mode. This simplifies taxes and reporting in the point of sale.
For the most specific tax calculation, you may use Taxes as a Line Item mode. This is can be set in Channels Settings at Apps > Shopify > Taxes:
For Taxes as a Line Item to function correctly, you must have 2 Tax Codes in Point of Sale; "Shopify Taxes" and "No Tax", both with a rate of 0%.
If your business is based in the United States and you wish to use this mode, we recommend checking “I want to specify taxes automatically” in Shopify Tax Settings. This will provide the most accurate tax calculation within Shopify. Simply go to Settings > Taxes in Shopify, click United States, and check the “I want to specifiy taxes automatically” checkbox.