That's fine for lots of people, but I'm not sure it's appropriate to be soliciting for tips in a job that's not traditionally tipped. If I were from a country not familiar with US tipping norms, I might feel obligated to tip, having heard that it's customary at US restaurants. Perhaps after I conduct a sales meeting, I should pass around a tip jar to my prospect's team.

What I'll say, is that it was likely not displayed in a pressuring way, so the tip jar is fairly harmless. If you don't want to tip, don't tip (not the same at a real restaurant). But I can see where customers would get annoyed at these tip jars popping up everywhere for conducting a 30 second transaction with someone who gets a regular paycheck.