Many stores have a minimum sales amount in order to use a credit card. ($5 minimum or $10 etc). In order to reach the minimum, people purchase items that they would not have otherwise purchased.
Is there not a halacha prohibiting “convincing” a person to buy something they do not really want to buy? Would that halahca apply in this case?
A store is entitled to put a minimum on CC purchases, so as to make it profitable for them. In addition this is a fair marketing tool to offer incentives to push people to buy more.