I’ve seen walls decorated with bills many times in many types of places.
Because I often see them as a tourist, many of the places cater to tourists and have the bills signed with the cities or countries the people come from. If the latter, they’ll often be bills from many countries.
Some bars do this as well, but I’m not enough of a bar person to know whatever local custom generated this.
Thinking about it, the majority of places I remember this are from the northeastern U.S. and Canada, so this may be a regionalism. But they’re common enough that I don’t give them much thought so it surprises me how many people here are unfamiliar with them.