A recent poll conducted by Marketplace found that most people don't tip and that those who do tip tend to give $1, though some just drop the change they're handed right into the tip jar.

But should you tip your barista? And if so, how much? Those deeper questions seem to be open to ongoing debate. A recently released Starbucks app that allows customers to tip with their orders — .50 cents, $1 or $2 — would seem to imply that some tip is expected.

Some people argue you should always tip. Many etiquette experts insist that tipping baristas, who in many states make at least minimum wage, unlike, say, bartenders, who are paid a "server's wage" on the understanding that they will make up for it in tips, is not required. But they also point out that it's a nice thing to do, especially when someone carefully traces a picture in your cappuccino foam and hands it to you with a smile, gracefully fulfills your complicated order, or adds a little extra whipped or other frothy accessory to make your day a little brighter.

The amount is up to you — and, no, a handful of change is not an insult, or shouldn't be — but if you're a regular somewhere and want to keep getting especially good service, it's probably not a bad idea to throw something in the can.

"I know your coffee is already overpriced, but a dollar bill in a tip jar earns you infinite goodwill," an unnamed barista has advised in Reader's Digest. "I'll carry that happy feeling over to my interaction with my next customer. Karma works, and it only costs you a buck."

In fact, if you factor in a New York Post story that ran a few days ago, you may conclude that tipping your barista is actually tantamount to hazard pay: Baristas, the tabloid reports, are at high risk for repetitive stress injuries.

Such injuries are "very common, and usually chronic," Phaeleau Cunneen, a New York-based physical therapist who specializes in hands, told the Post. To make an espresso, "you have to stamp the espresso, push it into the machine, then turn the knob — and the person running the machine is probably making 100 to 300 cups a day, maybe more." Add to that all the lifting and moving behind the counter, and "the elbows are taking a big strain."

Barista advocate Alex Bernson told the paper that an informal survey he conducted for the coffee news and culture site Sprudge found that 55 percent of the 475 baristas who responded had repetitive stress injuries.

So maybe — to help those baristas with any espresso-elbow medical bills — we all really should tuck a little something into that tip jar, or brew a pot at home to give them a break.