The New York Times says that:
At Target, for example, interchange fees represent the second-largest store-level expense, behind payroll. The costs are similarly eye-popping at Home Depot, where officials say they top the price of health care insurance for employees. “The amount of money we’re spending on interchange would put 10 associates in each of our stores,” Dwaine Kimmet, vice president of financial services for Home Depot, said at a recent conference on credit card fees.
(via the Consumerist)