VAT to Assets

How can you add VAT to an asset? I am able to retire an asset and add VAT, but I am confused with how it works when you are adding an asset with VAT. What if the VAT is inclusive? When you add vat in the "Tax" page (link at the asset acquisition details page) - are you supposed to see the VAT amount when you return to the asset acquisition details page? PeopleBooks does not add much explanation. We have Tax Codes set up with percentages - can the percentages change? Can you calculate the VAT by those percentages?