We are a small business.  More of our customers are using credit cards to pay their invoices.  We want to charge our customers a service charge when they pay their invoices by credit card to offset the charges we receive from the credit card companies.  How do we do that in 50?  Some customers pay some invoices with a credit card and some with a check.  Also, we have to account for that so it won't show up at the end of the month as income.  Any suggestions will be helpful.  Hopefully, I've explained our situation clearly.  Thanks.