Price X Percentage

[Davee]

I've set up a field in the products table as percentage

 

here's what I'm trying to achieve

 

i.e. (price - ?10.00) x (percentage - 1.25) = price - ?12.50

 

Is the a way to hard code this into currencies.php instead of having to go through every file & having to change to products_price*percentage?

 

Thanks in advance

 

Dave