The penny and nickle cost more to produce than they are worth in face value. Simply put, the more of them we make the more money the USA loses. Eliminating them makes obvious sense. You would also have to drop the dime so proper change can be given in certain situations.
Moving the dollar and five dollar bills to coins also saves this country many millions per year. Coins stay in circulation much, much, longer than bills and it is not debated that this would save money.
This causes little inconvenience for anyone, it saves hundreds of millions per year, and shows the average citizen that the government is actually doing something.