Tax Defaults and Geolocation

[cyanoxide]

I'm in a weird situation where I'm based in the UK but my primary market is USA because of this I'm using Dollars as my shops default currency. I've got my taxes set up but if geolocation can not detect where the user is from it defaults to "no tax" regardless of where they are.

 

This means people see lower prices on the site then go through the checkout process and then when they put in an address it bumps up to the correct price which annoys people as the thought the price was lower. I wish to make it so that by default it adds the tax and then lowers it after checking the address. It may cause less people going through checkout but we will have happier customers because the price will go down rather than up.

 

How would I go about setting up Prestashop to work in this way so by default it adds tax and removes it when required rather than having no tax and adding it when required whilst still maintaining geolocation functionality.