Is there a better way in C# to round a DateTime to the nearest 5 seconds

DateTime now = DateTime.Now;
int second = 0;

// round to nearest 5 second mark
if (now.Second % 5 > 2.5)
{
    // round up
    second = now.Second + (5 - (now.Second % 5));
}
else
{
    // round down
    second = now.Second - (now.Second % 5);
}

DateTime rounded = new DateTime(now.Year, now.Month, now.Day, now.Hour, now.Minute, second);

DateTime now = DateTime.Now;
  DateTime rounded = new DateTime(((now.Ticks + 25000000) / 50000000) * 50000000);

public static TimeSpan Round(this TimeSpan time, TimeSpan roundingInterval, MidpointRounding roundingType) {
        return new TimeSpan(
            Convert.ToInt64(Math.Round(
                time.Ticks / (decimal)roundingInterval.Ticks,
                roundingType
            )) * roundingInterval.Ticks
        );
    }

    public static TimeSpan Round(this TimeSpan time, TimeSpan roundingInterval) {
        return Round(time, roundingInterval, MidpointRounding.ToEven);
    }

    public static DateTime Round(this DateTime datetime, TimeSpan roundingInterval) {
        return new DateTime((datetime - DateTime.MinValue).Round(roundingInterval).Ticks);
    }

new DateTime(2010, 11, 4, 10, 28, 27).Round(TimeSpan.FromMinutes(1)); // rounds to 2010.11.04 10:28:00
new DateTime(2010, 11, 4, 13, 28, 27).Round(TimeSpan.FromDays(1)); // rounds to 2010.11.05 00:00
new TimeSpan(0, 2, 26).Round(TimeSpan.FromSeconds(5)); // rounds to 00:02:25
new TimeSpan(3, 34, 0).Round(TimeSpan.FromMinutes(37); // rounds to 03:42:00...for all your round-to-37-minute needs

static int Round(int n, int r)
{
    if ((n % r) <= r / 2)
    {
        return n - (n % r);
    }
    return n + (r - (n % r));
}

DateTime rounded = roundTo5Secs (DateTime.Now);

secBase = now.Second / 5;
secExtra = now.Second % 5;
if (secExtra > 2) {
    return new DateTime(now.Year, now.Month, now.Day, now.Hour, now.Minute,
        secBase + 5);
}
return new DateTime(now.Year, now.Month, now.Day, now.Hour, now.Minute,
    secBase);

// truncate to multiple of 5
int second = 5 * (int) (now.Second / 5);
DateTime dt = new DateTime(..., second);

// round-up if necessary
if (now.Second % 5 > 2.5)
{
    dt = dt.AddSeconds(5);
}