Didn't we just go through where this code is built?
You could build a function for this or add a paramater to the existing function so that the default way sends everything and the paramater says just send the percentage ... or whatever you want to do with it ...
Of, just add the whole price and discount by the add to cart so the customer can always see it ... both where it is now and at the button ...
Or, you can get even fancier and have the Add to Cart show the current price based on Attributes/Quantity ... and the top say the normal price display ...
Takes a lot more customization but it does look very cool ... it just depends on how much work you want to put into this or have someone write it for you ...
