In November, 1989, Representatives James A. Hayes, of Louisiana, and Jim Kolbe, of Arizona, having had just about enough of all this, introduced the Price Rounding Act. Its purpose was to phase out the penny by requiring that all cash transactions be rounded to the nearest five cents. The bill was actively opposed by Americans for Common Cents, a lobbying organization that had been founded specifically to defeat the legislation. A.C.C.'s main funding came from Jarden Zinc Products, which is one of the nation's largest producers of zinc, and which has supplied the U.S. Mint with penny planchets since 1982. [...]
Coinstar charges most of its customers 8.9 per cent of any amount they feed into a machine. The fact that consumers happily pay this considerable fee suggests that they wouldn't be bothered by the vastly smaller penalty that rounding to the nearest nickel might entail. Of course, eliminating cents would also eliminate the middleman -- in this case Coinstar, which annually processes about forty billion coins, more than half of which are pennies. Not surprisingly, therefore, Coinstar has been an advocate of preserving pennies. Since 1998, the company has conducted an annual currency poll, which always shows that Americans still love pennies and would prefer to continue getting rid of them by collecting them for months or years and then paying Coinstar to put them back into circulation, instead of getting rid of them once and for all by having the Mint stop making them.
See also The Megapenny Project.