Credit card prices

Why is it when your approaching a gas station you see the prices, and when u go to the pump and pay with your credit card its at a higher price.I cannot recall years or maybe months before that being the case.Is it now the gas stations are trying to suck us dry like the oil companys.Or maybe there worried about our credit cards getting maxed..Imagine that.If that being the case ,maybe they will let us put gas on lay away. hybrid cars