Say you have a DateTime object like this:
DateTime someTime = DateTime.Parse("00:00:38");
How would you round this up to the nearest minute? There isn't a built in function to do this so you have to use a little bit of maths to get there. There are 60 seconds in a minute. We already have 38 seconds on the clock. So we need to add on 60 - 38 = 22 more seconds.
In code this looks like:
DateTime RoundUp = DateTime.Parse("00:00:38"); RoundUp = RoundUp.AddSeconds(60 - RoundUp.Second);
Now our RoundUp contains "00:01:00".
To round down we use the same idea:
DateTime RoundDown = DateTime.Parse("00:01:38"); RoundDown = RoundDown.AddSeconds(-RoundDown.Second);
The AddSeconds() method doesn't actually alter the DateTime its working on - it just returns a new one. This is why I assigned the DateTime to itself in the examples above.