Here is how you can add tax in shopfront:
Step 1: Click on 'More' on bottom of the main page
Step 2: Click on Shopfront
Step 3: Click on Settings at the bottom of the screen
Step 4: Scroll down and click on 'tax'
Step 5: Enter the tax percentage
Step 6: Click on apply changes
Note: If you don't want to include Tax, click on the disable icon
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