Tipping when prompted: yay or nay?

For those of us in North America, we've all been to a cafe and ordered a beverage to go, only to be met with that familiar "Choose tip amount" prompt...

Then comes the dilemma: do I tip?

My gut reaction is to tip 12% and save face — "I don't want to look like a cheapskate". However, I have never been to this cafe before. Do I really need To Insure Prompt Service after filling my travel mug with joe? Yet, in the back of my head, I know that their employer is paying them as little as possible, guilting patrons like me into filling the gap in their wages.

I'd indignantly prefer to use my tips on the cafe I frequent, the baristas I know, or the times I choose to and not because I was asked. Perhaps withholding it and "voting with my money" for the business owner to pay their staff fairly instead is the best choice.

But they're underpaid.

As you can tell my monologue, I have yet to find an answer to constantly being asked to tip in situations where I would not have of my own accord.

Would you tip?