I think I want to tip my waiter only a penny.
What is your reason for only wanting to give your waiter a penny?
They neglected to ask me if I wanted any dessert before bringing me the check.
The waiter gave you good service, but simply forgot to ask you if you wanted dessert. It is bad form not to tip 20%. Give the waiter the full tip and just let them know about their omission.
I can't tip because I only have one penny.
This just seems like a small mistake to only give the waiter a penny. If you are only going to give a penny, you are better off simply not tipping at all. Maybe just add the tip onto your debit card instead.