Replace or eliminate the penny. In 2011 the US mint lost $60,200,000 producing it as each penny costs 2.41¢ to make.

From Wikipedia:
As of 2012, it costs the U.S. Mint 2.41 cents to make a cent because of the cost of materials and production... The loss in profitability due to producing the one cent coin in the United States for the year of 2011 is $60,200,000. This is an increase from 2010, the year before, which had a production loss of $27,400,000.