Why do pennies and nickels have smooth edges?

Pennies and nickels have smooth edges whereas dimes, quarters, half dollars, and dollar coins have rough edges. When dimes, quarters, etc. were first minted, they were composed mostly of silver and copper. The value of these materials led many underhanded people to shave off the edges of the coins in hopes of selling the collected shavings. The coins were being devalued, yet they were still being accepted at full value in commercial businesses and banks that were not aware of the shaving. In 1965, however, dimes, quarters, etc. were minted with rough edges to prevent shaving. If a bank noticed that the rough edge of a quarter, for example, was shaved, it would refuse to accept the quarter. From the beginning of their production, pennies and nickels were composed of less valuable metals such as zinc, aluminum, and copper, so shaving them carried little incentive. Today, despite the fact that dimes, quarters, etc. are not made with real silver, the characteristic rough edges have still been kept in their production.