[MrTelly's answer is the most sensible, but let me add to it a bit]
I haven't heard the word "tardy" since kindergarten!
Perhaps everyone who arrives on time should receive a gold star sticker, and anyone who is late doesn't get one. A poster board with everyone's gold stars can be displayed in the lobby so that visitors can easily see who the Good Little Children are.
Seriously, the notion of punishment in a professional environment is ludicrous. People who are late miss out on part of the meeting. If that causes their performance to drop or impacts the project, they get reprimanded for that, and eventually fired if the problem isn't corrected.
If you treat your developers like children, don't be surprised if they act like children. And vice-versa.