I saw a story on the news about some gas stations giving a discount for cash sales. Could we implement that at a theatre? I don't think we are allowed to charge fees for a credit card transaction so could we legally offer a cash discount instead? Would customers go for this?

I saw a promo on CNN about it but missed the story.

As far as I know, your credit card merchant agreements do not allow this. Although I have not looked at mine in years.