How to deal with Rounding-off TimeSpan?

Question

I take the difference between two DateTime fields, and store it in a TimeSpan variable, Now I have to round-off the TimeSpan by the following rules:

if the minutes i

Answer 1

How about:

public static TimeSpan Round(TimeSpan input)
{
    if (input < TimeSpan.Zero)
    {
        return -Round(-input);
    }
    int hours = (int) input.TotalHours;
    if (input.Minutes >= 30)
    {
        hours++;
    }
    return TimeSpan.FromHours(hours);
}

Answer 2

TimeSpan is immutable, so you have to create a new one. This is also a perfect case for using extension methods in C#:

public static class TimeSpanUtility
{
   public static TimeSpan Round( this TimeSpan ts )
   {
       var sign = ts < TimeSpan.Zero ? -1 : 1;
       var roundBy = Math.Abs(ts.Minutes) >= 30 ? 1 : 0;
       return TimeSpan.FromHours( ts.TotalHours + (sign * roundBy) );
   }
}

// usage would be:
var someTimeSpan = new TimeSpan( 2, 45, 15 );
var roundedTime = someTimeSpan.Round();

Answer 3

You can use

double v = span.TotalHours;     
v = Math.Round(v, MidpointRounding.AwayFromZero);
span = TimeSpan.FromHours(v);

It depends on whether I understood your rules for negative values correctly.