There's nothing you can buy with a penny -- not even, as retirethepenny.org points out, a penny (it costs 1.7 cents to make one). Try handing over a hundred or more pennies in a single transaction, and you'll receive a thousand death stares and a lifetime ban along with your goods. There simply isn't a use for this coinage anymore. Unless, of course, you are Big Zinc. The zinc lobby does exactly that: They lobby (hard and successfully) to ensure that pennies continue to be created using zinc rather than steel. They fight for the penny's right to exist, claiming inflation would spiral out of control if we no longer had access to these useless, wallet-destroying coins ... even though countries like Canada and Australia have already done this, and they seem to be fine.
The world if you had to pay $2 instead of $1.99 for your candy.
Zinc doesn't stand alone in their defense of the penny. Coinstar has also thrown its weight behind the coppers, bankrolling polls aimed at "proving" that Americans would prefer to keep the coins around. And so we continue spending millions pumping them out year after year -- although it's been rumored that the penny's production will finally be halted in 2017. So prepare for the apocalypse, everyone!