Give Jenny a choice.

Seeing the brunette standing there in the sundress you picked out, you decide to have some fun. You have barely altered her mind, so much of her behavior is fairly genuine.

The small mountain of clothes you've selected will cost a lot of money. You could easily coerce the manager into simply giving them to you, but that would be boring. Where is the fun in having all the power in the world of you have to tell everyone what to do all the time?

"Jenny."

"Yes sir!"

"You are a fine servant and have served me well."

She beams with pride. "Thank you, sir!"

"I also see that you are wet with desire. You want my cock, don't you?"

She blushes furiously but doesn't deny it. "Ah! Well, you see. I-"

"You don't have to say it. It would be cruel of me. I will say this instead." You move to stand closer to her, looming. You are enjoying the new height and power that you feel in your body. "I am about to leave this store and you will probably never be in my presence again. If that's how you'd like this to end, stay where you are and know that you have been a fine servant and that have pleased me in that capacity. Or, you can take my selections to the counter and purchase them with your own money. Do this, and I will know you desire to be my cocksleeve. I will take it from there."

You step back and Jenny is breathing heavily, staring straight ahead at your chest.

You decide to give her a few seconds to process the ultimatum.