This market resolves to YES if, in early 2030, cash transactions at stores in the US do not, by default, involve pennies. This could be because the government stops minting pennies, because stores adopt a policy of rounding prices, or for some other reason.

The smallest unit of currency in the US is the cent, one hundredth of a dollar. The "penny" is a one-cent coin. It has been the smallest-denominated coin since 1857; during that time its value in real terms has decreased substantially. There have been a number of proposals to abolish the penny

https://en.wikipedia.org/wiki/Penny_debate_in_the_United_States

but so far none has been accepted.