Pennies and nickels are no longer necessary and cost more to make than they are worth. Many other countries have already gotten rid of one if not both of these coins. The US waste millions of dollars a year to mint these coins when that money can be used on more useful things or at the very least lower our annual debt.
http://youtu.be/y5UT04p5f7U
http://youtu.be/77C47XYm_3c
http://youtu.be/nU4E6SSy5Yg