DateTime Round Up and Down

Question

Ive been looking for a proper rounding mechanism but nothing I find seems to be exactly what I need.

I need to round up and round down seperately and I also need to acco

Answer 1

This will let you round according to any interval given.

public static class DateTimeExtensions
{
  public static DateTime Floor(this DateTime dateTime, TimeSpan interval)
  {
    return dateTime.AddTicks(-(dateTime.Ticks % interval.Ticks));
  }

  public static DateTime Ceiling(this DateTime dateTime, TimeSpan interval)
  {
    var overflow = dateTime.Ticks % interval.Ticks;

    return overflow == 0 ? dateTime : dateTime.AddTicks(interval.Ticks - overflow);
  }

  public static DateTime Round(this DateTime dateTime, TimeSpan interval)
  {
    var halfIntervalTicks = (interval.Ticks + 1) >> 1;

    return dateTime.AddTicks(halfIntervalTicks - ((dateTime.Ticks + halfIntervalTicks) % interval.Ticks));
  }
}

To take care of truncating the seconds, I would simply subtract the seconds and milliseconds from the date-time before sending them into the rounding functions.