we found some mystical calculation error in our shop, and after testing some other shops, we've seen that this problem is everywhere the same. In the calculation of the VAT, there is a difference between the calculated price by drupal and my calculator depending on the amount of the product. It seems to me, that there is a problem with the decimal. How can i fix this?

Thanks for any idea, but i think this is a maybe unknown problem nobody seen before, because the summary and everything else is o.k.

Sunny greets from germany