Lately, I’ve noticed a card war brewing.On one side, stand the Banks and Credit Card firms. They get paid a percentage of every sale when you swipe your Amex, Master Card or Visa in a credit card machine.On the other side, are the Retailers.In the middle, the Consumer. The battle between the two giant sectors means that choices (and potential costs) are multiplying — if consumers become aware of them.The battle is over that 3% or so processing fee (it varies) when you swipe your card at a store.