Thank you for your help.
The value I am looking for is the GrandTotal. For European customers this value should not include shipping cost. Therefore I tried calculating a EuropeanGrandTotal. But like I said, all I am getting is the wrong calculation or empty pages.
My calculation looks like this:
item 1: 4.00
item 2: 6.00
tax: 1.90 (that is 19 % of the subtotal)
total: 4.76 (my try to calculate the EuropenGrandTotal adds 19% only to the first item, instead of the subtotal. The total should be 11.90)
So, my question is, how do I generate a European GrandTotal (one, that does not include shipping cost).
I also tried adding a cart object $nameEuropean. For that cart object I did not specify shipping cost, and I changed all $name to $nameEuropean on the success page. I still end up with the same (above) calculation.