Earlier quoted context omitted.
As the article points out, there are laws that say people who pay via SNAP debit cards "cannot be charged more than others". If cash payments are rounded down, but debit card payments aren't, they are in violation of state law. The article also points out that rollback of pennies in Canada and other places were planned, addressing these kinds of issues. USA is doing it with no such planning.
The article also points out that some states and a lot cities require retailers to provide exact change. Congress would need to pass legislation to allow rounding nationally. I'm guessing in the meantime they'll continue holding pennies from previous years?
We unofficially drop the coins/bills when the reach ~US$0.03, so now we dropped the AR$50 bills and everythig in cash is rounded down to AR$100 (US$0.07).
(The only exception is the photocopy shop 2 blocks away from home.)
Credit cards are charged the exact ammount, with cents that are irrelevant.