Quote Originally Posted by pilou2 View Post
I think I figured out part of the problem. In my currency with rate 155 (JPY) I use 0 decimal. It seems that currency conversion in cart rounds to 0 decimals before conversion:
Product price 48.34 becomes 48 which multiply by 155 gives 7440 which is exactly the wrong price I got in cart without tax.
Second product price 35.00 has 0 as decimal. This is why price after conversion is still right. I don't know where it is in the code yet.

When displaying prices with tax:
Product 1: 48.34 x 1.1 = 53.174 ----> 53 x 155 = 8215 Which is what I got.
Product 2: 35.00 x 1.1 = 38.5 ----> 39 x 155 = 6045 Which is what I got too!

Rounding to new decimal setting should be done after conversion.

Calculation in last checkout screen is different and there might be something else to figure out...
Thank you for taking the time to check this out. It would help me to reproduce and then correct the issue if I could verify:

Store currency, number of decimal digits (sounds like 2)
What is the 1.1 that multiplies the product pricing, for example 48.34 x 1.1 = 53.174
Store currency, converted to JPY with a 155 conversion rate.