[Veveseinlep]

Pennies and nickels were being produced at a loss (not sure if this is still true, since commodity prices took a dive). Dollar bills are still profitable to print.

For pennies, this has been true since the earky seventies. The BEP changed the composition of nickles and quarters in that same era, to prevent their following. Recently, pennies and nickles both at deficit, as much from OH/handling costs as materials. The paper dollar gets lots of handling and is worn enough to be pulled from circulation in 18 months on average. The other bills last 3 to 5 years in circulation. So there have been suggestions to use only dollar coins. To do that, most cash registers would need to open a slot, thus the rumors that pennies and paper dollars are headed into history. So far, Congress remains unconvinced and won't authorize or fund a switchover.

Side note, the back of the penny changed again this year, guarenteeing high demand. Not a good way to convince Congress to allow the penny to go obsolete creating a space in registers for $1 coins.