Pennies and hundred dollar bills

In the latest edition of the Eastern Economic Journal there's a fascinating debate between Robert Whaples and Raymond Lombra over whether the penny should be eliminated (o.k., 'fascinating' may be an overstatement. Somewhat.) Basically, Lombra is worried that the consumer will get screwed as companies round up to the nearest nickel and a couple of other things that seem bizarre to me. Whaples refutes these arguments, winning the debate by quoting from Gregory Mankiw, who proposed in an op-ed piece for the Wall Street Journal that all politicians take the following oath:

"This year I will vote to eliminate the penny. The purpose of the monetary system is to facilitate exchange, but I have to acknowledge that the penny no longer serves that purpose. When people start leaving a monetary unit at the cash register for the next customer, the unit is too small to be useful. I know that some people will be upset when their favorite aphorisms become anachronistic, but a nickel saved is also a nickel earned."

While we're discussing monetary reform, I have another proposal: replace the 100 and 50 dollar bills with nice, hefty coins about the size of the Eisenhower dollar but twice the thickness. This simple reform would cripple organized crime and terrorism. How are you going to smuggle $5 million across the border to Mexico to pay for that shipment of cocaine? How is al Qaeda going to pay for box cutters and airline tickets for its agents in the U.S.? These groups will face the uncomfortable choice of filling five times as many suitcases full of bills, or use the banking system - and then we've got 'em!