I think it is a bad idea.
You can offer an ATM for an alternative, but it is 2010 and people love their credit and debit cards. It is about convenience and swiping their card for the amout they are spending and walking out the door appeals to our customers. Believe me I wish it was 1990 again and this was an all cash business, but times have changed and people spend more money when they use their cards. It is hard to change your thought process on this if you are an old school guy from way back, but people use their cards and they are here to stay.
good luck on your decsion.
Tony