Making & using cash pennies cause far more trouble for the merchant, consumer, banks & US mint than the pennies are worth.
We should program cash registeres to round off the toal to the nearest nickel. This will free space in a typical register for dollar coins. Using dolar coins will free space for $50 bills.
Encouraging cash transactions will stimulate the economy by removing the 2-3% "tax" charged by the credit card companies on all credit/debit transactions.