If you were late often, describe how many days you were tardy and why. You want to avoid being dishonest since the interviewer will call your previous employer as a reference. You also want to avoid acting like it is no big deal to be late, showing a lack of respect for your employer and coworkers.

"I was late to work twice last year. One time was because my wife accidentally took my car keys with her when she went to work, and I had to wait for her to bring them back to me. The other time was because there was a major accident on the highway and traffic was stopped for half an hour. Both times I called my supervisor to let them know I would be late, and they did not have an issue with my tardiness since I called them. Typically, I arrive to work half an hour early, so these were unusual circumstances for me."