When I was working minimum wage at a gas station many eons ago, we would have '2 for $x' specials where x is less than 2 times the individual price of whatever item.
People would often not want to buy 2, but I would ring up 2 in the till for the special price and charge them for the single. Then when the next person did the same, I would charge them for the other single.
So over the day, I would sell 10 energy drinks at say $4, but ring them up as 5 '2 for $6' specials. This would put the till up by $10, and then I would use that $10 to have a free meal.
I worked at a restaurant that had a contest once for which server could sell the most orange juice. At the time, sodas were $0.99 and orange juice was $1.98. So, any time a table ordered 2 sodas, I'd ring it up as 1 orange juice. I won by a landslide. The customers would occasionally ask why their receipt had orange juice, but I'd just explain it's the same price as the 2 sodas, and that was the end of it.