How do I set my tax to 8.25%

[AJ12]

I am trying to  set my sales tax to 8.25% and when I go into items on the dashboard and then to sales tax it says variable.  I need to change this to read 8.25% consistently.  

Please help.  

[VanKalkerFarms]

Once you change or add a tax here. https://squareup.com/dashboard/items/taxes.  You can then click "apply tax to items" and it will bring up a pop-up that allows you to choose which items to apply it to.

You can go item by item and choose the tax you want to be applied also.