If you want to sell things on it, I'd set it as retail. Then it will definitely work the way you want.
I've used some lots for multiple purposes, and in order to get the right employees without hiring them, I switched lot types during play. I switched between cafe and nightclub mostly, and Sims gathered around the appropriate objects on the lot. An employee would show up for the current lot type, and any other employees left.
During this time, the cash register wasn't in use and nothing was for sale. Once the lot was set as retail I couldn't switch back without going to manage worlds. I still had the ability to hire Sims for the various objects on the lots, though.