It would be great for RE to automatically adjust the total receipt amount based on funds codes that get receipted and fund codes that do not get receipted. For example, a donor gives $100 cheque of which $20 is to purchase a t-shirt and $80 as a donation. The receipt amount should reflect this automatically.

For the t-shirt example, if you attach a "Benefit" of a t-shirt with a $20 value RE will automatically adjust the receipt amount to $80.