The Tax Zones interface is used to determine when a particular tax should be applied. To add a tax to a specified zone, click on the inspection tool beside the region you want to apply taxes to (for example, to apply a federal tax, add it to your country zone, e.g. "Canada").
Use the drop-down menus to select a tax from the list you created in the "Tax Rates" section.
You can also indicate if this tax is compounded or added to taxes which may apply to sub-regions.
Click "apply" to save your tax settings for that zone.
You can add other countries or zones within a country by clicking on the applicable "add" button. Enter your tax information on the right and click "apply" to save the tax settings for the new region.