If a product cost say 100 and the tax part of that price is 20. After OT countdown have been put in use and say the offer now is 50 and tax of that should be 10, it nust do not recalculate tax.

Is this a bug or is it not ment for countries who need tax calculated?

Have a look at the photo below. Can it be fixed so tax can be adjusted? You see the amount 39,80 is not adjusted to reflect the new price.