The reason why is that I am trying to create a VAT Exemption store which does not charge VAT on the product, but will calculate VAT on the shipping. However, when I use a 'Group' discount structure of 20% (UK VAT rate), it doesn't calculate the VAT correctly which is causing us issues.
So... I have set-up Specific pricing for the Product (no VAT) and then would like to do the same for Shipping, that way there is no calculation for VAT because I have already done it.