Pennies have been made with an alloy comprised of 97.5% zinc and 2.5% copper, but pennies minted before 1982 are 95% copper and 5% zinc. The price of copper has more than quadrupled over the past 10 years.
So a penny produced before 1982 is worth 2.2 cents based on the metal it contains.
On eBay, a lot of 5000 pennies has a face value of $50, but it will sell for $60.