Do people tip Walmart?

Is it common for customers to leave tips at Walmart? I've noticed that in some service industries, like restaurants and hair salons, tipping is expected as a way to show appreciation for the service provided. But when it comes to shopping at big retail stores like Walmart, does the same custom apply? Are there any specific instances where a Walmart employee might deserve a tip, or is it generally seen as unnecessary? I'm curious to know if the culture of tipping extends to retail settings as well.