So how does "Product Price excl. tax" become "$83,33" when the tax is 20%. Shouldn't it be $80?
It makes it 16.67% tax... am I missing something?
When it comes to Shipping rates and even government taxes, they will vary per order, in the case of international orders, the shipping rates would change and even the taxes would change based on the country.
So it won't be possible to generalize a standard rate for a product. However, it can be done on the orders. Or are you thinking in other terms?