when I used to shop at Lane Bryant (back when I had a job that allowed me to blow $60 on a pair of jeans) if a certain salesperson was helping me, and I went up to pay for my stuff, I always made sure to tell the person manning the register that "salesperson" was the one helping me.

When I got to be friends with one of the salespeople, when I would go back to buy stuff, and that person wasnt there, I would still tell the cashier that that certain salesperson had helped me out and to make sure she'd gotten the credit for helping me.

If I had two people help, I'd try to make sure they both got the credit for the sale.