An audit requested by Senator Charles Grassley has uncovered a string of questionable credit card transactions by Pentagon employees.Grassley says the audit found a five hundred dollar tab from a topless bar in South Carolina called the “Bottoms Up” had been turned in as a travel expense. Grassley says a preliminary review of credit card transactions over the past two years has uncovered over 500 cases of fraud.Grassley says the key is forcing Defense Department employees to submit a valid receipt for every transaction — something that’s not happening now.Grassley says “heads have to roll” before the military-types will get the message. Nearly two million credit cards were being used by Defense Department employees last year.