I always make it a point to thoroughly search this forum, of Drupal's and the entire internet for that matter whenever I need to get some questions answered. That's what I did to what seems to be a simple feature to be expected of Commerce.

After going through hundreds of threads, trial and error and asking on Drupal forums I still got nothing.

Anyways, enough about my frustration and on with my question. I would really APPRECIATE any advice.

The gist of it: How do I set attribute price to be inclusive of VAT?

Details: I need an attribute to be added to a product and this attribute if chosen will reflect on the original price of the product. The product sell price is VAT inclusive. Adding the attribute price to the original product's price is easily achievable with this modules:
https://drupal.org/project/commerce_option
https://drupal.org/project/commerce_pricing_attributes

However, the attribute's price does not include in the computation of VAT and order only shows the VAT of the product's original price. Basically, the VAT row displays wrong VAT computation. Say for a $20 shirt with an attribute of 'Large' at an additional $1, order displays VAT(20%) as $3.33 when it should be $3.50 in total.

What I did so far: I edited the pricing rule that controls the attribute (Commerce pricing attributes calculation) and added the 'Calculate taxes for a line item' action. Also tried the 'Apply a tax rate for a line item' action to no avail. Re-arranged the weight and made sure the VAT is applied in proper order and still nothing. I was on custom installation so I tried the Kickstart package and mess about with it trying to achieve this after installing the two above modules and I still got nothing.

What's going on here and is there something I'm missing? I would really appreciate any advice from you guys. Thank you.