We have negotiated rates but do not want to display those rates to customers. I'd like to see a spot for a markup at the store and/or carrier level, either as a flat "handling fee" or as a percentage of the shipping charge. The reports would be able to include both "true charge" and "marked up charge". (In our case, we have no client-facing stores, and only want this feature for running reports at the backend, but I could see where other users might like it in that situation.)