Tax Rates are set up in your Account Settings where you can set up as many tax rates you need, then select which ones the system should use by default. These tax rates will be charged on the Rental Amount.
To set up tax rates to be charged on your add-ons and other fees, go to the Add-Ons & Fees, click "Edit" and select all the tax rates that apply to that item.
To set up default tax rates:
Go to Account Settings > Tax Rates
Click 'Add a new rate' and fill in the appropriate details and save, repeat as needed.
Click the drop down box and select all tax rates that apply
Click 'Save Default'
Refresh the browser window
The taxes will be shown as follows on the reservations, each tax item will have its own line displaying the name you have given that tax item. You can also click on the Rental Amount or other taxed line items to expand and see the breakdown of the taxes being collected for it.
When editing an add-on or Fee to include multiple tax items, simply "Edit" the add-on and select all the tax rates that apply from the drop down menu labeled "Tax Rate"