Paralell Payments on a single store

I just purchased MarketPress and all seems to be working well so far.

I have a single store setup, with a Gravity Forms form that allows people to submit a new item to the store for approval. I was wondering if there is a way to setup chained payments on the single store, so that I as the site owner can take a $1 fee from each product sold.

Any help would be greatly appreciated.