I'm not exactly sure how this works, but fastspring is an American payment solution, and there's a difference between domestic and international sales, perhaps it even varies per country. Simply put, we give fastspring the amount we want to receive from a purchase, and then depending on which country you live in, an additional tax may or may not be added. I have no idea how this really works, it's really confusing and I don't deal with this stuff even when I sell games on my own (the company Kreator helps me out by doing the administration), but prices does not include a possible VAT.
We list the price before any added taxes, as this is the price you will pay in many countries. Fastspring will let you know what the final price is before you place the order anyway. Also, we can not customize this, it's how Fastspring work.