Fix products price range filter (use the final product price - including tax)

At the moment, if you display prices including TAX (which you do have to), the price range filter will not behave as expected.

For example, if I set tax to 23% and then try to filter products by price in range 50 to 100 it will show products in range of 61,5 to 123. Which is clearly not what customer wanted to do.

Solution to the above issue can be not to display the product with TAX (price range filter works fine with base price), but that also mean that the tax will not be listed on customer order, which is problematic.

Personally, I consider this as a bug and not a new feature.