Tip Jar:

Another myth like ‘ exposure.’  Venues, particularly coffeehouses and small restaurants, like to try to convince musicians that getting fed, selling merch, and the tip jar, all of which cost venues next to nothing, should be sufficient compensation. Tip jars almost never provide even minimum wage for anyone other than street performers whose skillset is primarily geared toward maximizing tips - you really have to hit the crowd over the head to get them to cough anything up.  Like exposure, hospitality, or the merch table, the tip jar is largely a myth. Don’t buy it.