Here's another surprisingly interesting little micro-documentary from YouTube, this one about the U.S. one-cent coin, or penny:
An aside: The coins of most countries clearly show their value in numbers. American coins give the value in English words: one cent, five cents, one dime, quarter dollar, half dollar, one dollar. Americans grow up knowing that a dime is worth ten cents, but most of us don't realize that a "dime" isn't just a coin but the name for a monetary unit. Back when the U.S. was getting started, most Americans were used to English money, with four farthings worth a penny, 12 pence worth a shilling, and 20 shillings worth a pound. Thomas Jefferson (if memory serves) proposed an American system based on multiples of ten: 10 mills to the cent, 10 cents to the dime, and 10 dimes to the dollar.
The term "mills" still shows up sometimes in property tax rates, but pretty much nobody quotes the price of anything in dimes, so in practice the word "dime" really does mean just the coin. Labeling a dime "one dime" is hence close to useless. It should really be "ten cents" or better still "10 cents."