Every once in a while this strange bug occurs. After all the desired products are added to the cart, on the checkout page the calculations don't make sense at all (see attached screenshot).
The tax amount and subtotal both seem to be doubled, resulting in way too high of a Grand total!
When ordering the same combination of products another time, suddenly the right calculation is used and everything seems to be working fine.
I'm using Magento 220.127.116.11 and try to avoid updating to 1.8.1 during high season, so do you have any thoughts on how to fix this strange bug? No further price rules or discounts are set into place...
All support is highly appreciated!
Thanks in advance