The agency did not specify how long the inventory was expected to last, so it's unclear exactly when pennies will no longer be in circulation. Blanks are flat metal discs that eventually become coins,

The Treasury Department has placed its last order for blank pennies and plans to stop minting the one-cent coins as soon as that's exhausted.

The Mint has estimated that ceasing production of the penny will save the taxpayers an annual $56 million in reduced material costs.