Markup instead of discount??

Markup instead of discount??

Is it possible to have the discount field on an invoice or estimate be a markup instead? It's the very same functionality that I am looking for - to be able to markup an individual item by either a $ or a % and have that cost added (instead of subtracted) to the item cost. 
Currently, I use the tax feature to accomplish this, but it's very awkward to have "Markup 15%" listed after the subtotal. Plus, if I want to markup items at different rates, I end up with several "markup" lines in the totals section.

The utility of this feature for me is so that I can create an expense, ex: a subcontractor fee or materials, that I markup to bill my client. I need to know what amount I owe/pay a subcontractor, and have the markup added to the invoice (not to the expense item). 

It would be great to know if this is planned for development or could be added to your long queue...
Many thanks!