From what I remember, you can charge a single flat fee for using a credit card, but no percentages. At the time, I thought that 'sliding scale' flat fees (e.g.

From what I remember, you can charge a single flat fee for using a credit card, but no percentages. At the time, I thought that 'sliding scale' flat fees (e.g. < $100 is $0.15, > $100 is $1.50) were too close to percentages per the agreement.