Where in code is total_discounts computed?

[Kent88z]

I'm trying to determine how total_discounts is computed and where it can be changed in the code in 1.4.7.

 

Browsing through all the database tables I found only two references to the discount value in these two tables:

 

ps_orders (and the field is "total_discounts")

ps_order_discount (and the filed is "value")

 

The problem is the amount is computed after tax so the discount value also includes tax. I need them computed and stored excluding tax.

 

Any ideas where I can make this change?