I would disable the built in total calculator on the total element and use Jquery to provide it for you.

Hi Eric, thanks so much for your time and assistance so far.

I think what im wanting will prove to be too difficult to achieve.

If instead I looked to just charge 5% of the product price, without all the extras would that be more realistic to achieve?
It would work out roughly the same, in that PayPal transaction fees are roughly covered without loss to the client.

So the customer selects by radio button to either choose a trophy or Product2.
Trophies (id="item8_select_1") are individually priced from the dropdown list or instead chooses Product2 (id="item55_select_1") priced at £199. Then the 5% is just based on this selection and not the rest of the extras which the customer is able to add onto the order.

And then the price of this choice + 5% is added to the cart total.

Would that be achievable?

Let me look a a few scenarios.

Ok, Thank You Eric