Login to your account at https://squareup.com/us/en and go to your dashboard. On the dashboard, go to Items → Sales taxes. Click on Create a Tax. There, you can create a name for your tax, input tax percentage, etc. When you are done, click Save to add your new modifier set. Then, you can click Apply to Items to select items that you want your sales tax to apply to, or click Select All if you want the sales tax to apply to all items, and click Save Go to https://squareadmin.grubbrr.com/ and click on the Sync Data from Square icon (at the top right corner) to sync your changes. Finally, click on the Tablet Icon on the top right corner to sync data to the kiosk.