Apply a single tax to every order.

Hi,

First, if you sell worldwide, you will have to create one "world" zone via the menu System->Zones and include all the countries as sub zones.
Then, you will have to make sure that you have the "default tax category" selected in all your products
Then, you will have to create a "tax rate" of 8.9% via the "manage tax rates" button of the menu System->Taxation
Then, you will have to create a new tax rule via the menu System->Taxation with the "default tax category" selected, your tax rate selected and either the world zone or your country zone (if you only ship to your country).
Finally, if you ship to your country only, you will have to change the "main tax zone" option of the configuration to your country.