[TYPO3-shop] basket: false price because of extra addition of hidden variable numbers

[Jörg Petersson]

Hi,

the basket of my shop tt-product 2.5.7 shows a strange behavior:

I order 10 pieces of item A for 21 (netto 17,65 --ok) makes 210 incl. 19% 
VAT --ok
no other item in the basket
The total sum is 267,54 instead of 249,94
and says: the netto-sum is 226,51 instead of 176,50 >> difference: 50,01

and now only 1 item:

I order 1 piece of item A for 21 (netto 17,65) makes 21 incl. 19% VAT --ok
no other item
The total sum is 65,28 instead of 21
and says: the netto-sum is 56,15 instead of 17,65 >> difference: 38,70

What may that be? It seams to be a variable of somewhat and somewere. Or did 
I do something very stupid?

Do You know?

Thanks

Joerg