If we're talking about in the USA, land off the sub- minimum wage for tip-earners, I only ask one question of those who would withhold their tip in this particular circumstance.
If you messed up at work - didn't lose the sale, just delayed the remittance - and you owned up to your boss and he said okay, you get your base salary, but you didn't earn the commission. And I'm writing you up. Thanks for your honesty.
How you liking that? Do you like it more if that commission was what you're counting on to make the mortgage payment?