What are tax zones?
Tax zones determine the tax rates applied for any country/state you want to sell to.
You must add a tax zone for every country you want to sell to.
You can add 'Rest of the World' as a tax zone, which serves as a fallback for anywhere in the world.
If you set the tax rate to be 0%, any items shipped to that tax zone will be zero-rated (no tax applies), use this for exports.
How is tax calculated?
In order to match how Xero works, we calculate tax on a per line item basis. The tax for each line item is rounded to 2 decimal places. We then add all the tax for each line item and that gives the total tax owing.