New discount feature

[RyanSmith]

Hello,

 

I'm trying to write a feature that allows a customer to enter a employee code to get a 50% discount on products. I was wondering if I can implement this feature by creating a new orders_total module, or do I have to edit the code in a bunch of different checkout pages. Does anyone have any idea how to go about doing this. If you have any suggestions or information about how this process works, please let me know.

 

Thanks in advance