Through the iZettle Pro app there is the ability to setup multiple tax rates that can be assigned to products.
To setup or to change the tax rate of the system, go into 'Settings' and select 'Config'.
Scroll down to the section headed as 'Currency & Tax'.
You will see the option to setup your tax rates (up to 3) here.
Once the Tax rates have been set, these can then be assigned to existing or new products.
To assign these to a product, go to 'Settings' and select 'Products' and either create a new product or select an existing one. This will bring up a new window
Select 'Tax' and choose any of the previously set up tax levels for the product. Once you have chosen the Tax level, tap 'Save'.