For Performance Reports: Under 15 seconds round down to the minute, over 15 seconds or under 45 seconds, round up or down to the :30, over 45 seconds, round up to the next minute.
Unless I am specifically asked to do otherwise, of course. I have been asked for exact seconds, instead.
I have tried the minutes only/no seconds, but it sometimes raises questions, so I don't usually choose this method.
Random question: When you're reporting running times on your reports - do you include the seconds or do you round up/down to the nearest minute?