I have a registration for an event where the cost is based on how many of the sessions you wish to attend.
We have 4 sessions that cost $20 each. So I have a custom field for each session that adds $20 to the total when selected.
We also have lunch available for $10 (in another custom item).
We are offering a half-off and a 100 percent off discount.
But I don't want the discount to apply to lunch, just the sessions.
If you are talking about using discount codes, there is no way to do what you are asking. You can set the fee ordering of every field, fee/discount... all except discount codes. Guess that's something we need to add to the fee ordering setup.
Being able to set a custom field as being exempt from discount codes would be huge! Come to think of it we put this in the Wish List forum quite awhile back..