If you need taxes beyond primary and secondary or need to be able to support three decimal or 'tax on tax' tax rates you can set them up as an extra tax via the 'Add Tax' button.
In this section add a unique Tax ID followed by a brief description. Choose a flat rate or a percentage rate. Enter the rate as a number. Select wether this tax will be applied on top of other taxes. Choose yes or no for the Nonrecurring Tax. This is used if the tax is applied each day of the stay or only on the total, and is only applicable to users of the Property Management Systems.