public static string[] FifteenMinutesInHour(DateTime dateTime)
{
DateTime tmp = dateTime.AddMinutes(-dateTime.Minute);
return new[]
{
string.Format("{0:yyyyMMddHHmm}", tmp),
string.Format("{0:yyyyMMddHHmm}", tmp.AddMinutes(15)),
string.Format("{0:yyyyMMddHHmm}", tmp.AddMinutes(30)),
string.Format("{0:yyyyMMddHHmm}", tmp.AddMinutes(45))
};
}