It depends on your coteachers and who catches you. Last year I came in on time/slightly late because of waiting for the bus, and I was told by my co-teacher to get here earlier. For an entire year, I arrived 20 minutes early. My coworkers changed, and are pretty lenient. They will show up late on days they don't have first period, or we don't have classes because of some activity, so I don't feel bad about following suit. Some days, the principal and vice principal have caught me.
The key is to never act/look guilty. If you get reprimanded, apologize profusely and don't do it again. Having a good excuse helps, maybe you were out a second to go to the convenience store... The most important thing is to make sure it does not interfere with your classes in any way. Don't be late, be prepared and you will not have to worry about if they will resign you or not (if it's outside your performance, probably financial stuff).