Enter final product price in back end and show resulting discounted percent in front end

[EstherF]

Hi,

 

I would like to make a general change that applies to all products. I would like to be able to enter a final price and get the resulting applied percentage, instead of having to introduce a discount percent and get the final price. This way I don't have to go rounding off each discount in each product till I get my desired final price. 

 

Is this possible with a plugin or module or do I need to code this myself. If I hack this I will have problems in future updates.

 

Any ideas?

 

Thanks for your help!