How to compute UK style VAT in Craft Commerce? I'm encountering a problem with how to show UK style VAT tax on an item. I've created a tax rate called VAT at 20% that is included in the taxable subject. 

However when this tax is computed on say £8,000 rather than showing the tax as 20% or 1/5th = £1,600 it shows it as 1/6th = £1,333.33. I can't figure out why the tax isn't applying properly. Settings below:
Try unticking the This tax is already included in the taxable subject checkbox.

I would imagine that with this checked, Commerce assumes that the prices entered for products already have tax applied, so the tax amount is calculated on that basis, hence it being 1/6 of the total rather than 1/5.