Why do pennies and nickels have smooth edges unlike all the other U.S. coins?

I was fiddling with a penny when I noticed this. How come pennies and nickels have smooth edges unlike all the other U.S. coins?

Picture of Why do pennies and nickels have smooth edges unlike all the other U.S. coins?
Re-design7 years ago
Dimes, quarters and above used to be made out of real silver or gold. The coins were first minted plain sided and some people would shave off a sliver of the precious metal. Do this enough and you had a little sack of gold or silver.  It technically devalued the coin.

The mint came up with the idea to roughen the edges of the coin so you could tell if they had been shaved.  Banks and retailers would not take the shaved coins anymore.

Then nickel and penny were not made of enough precious metal to require the rough edges.