First approach that came to mind:

1. Setup a tally table in your environment.

SET NOCOUNT ON ;

GO

-- Credit: http://www.sqlservercentral.com/articles/T-SQL/62867/

--DROP TABLE dbo.tally

--=============================================================================

-- Create and populate a tally table

--=============================================================================

IF NOT EXISTS ( SELECT *

FROM sys.objects

WHERE object_id = OBJECT_ID(N'dbo.tally')

AND type IN (N'U') )

BEGIN

--===== Create and populate the tally table on the fly

SELECT TOP 11000 --equates to more than 30 years of dates

IDENTITY( INT,1,1 ) AS n

INTO dbo.tally

FROM master.dbo.SysColumns sc1,

master.dbo.SysColumns sc2

--===== Add a Primary Key to maximize performance

ALTER TABLE dbo.tally

ADD CONSTRAINT PK_Tally_N

PRIMARY KEY CLUSTERED (n) WITH FILLFACTOR = 100

--===== Let the public use it

GRANT SELECT, REFERENCES ON dbo.tally TO PUBLIC

PRINT 'Created tally table.'

END

GO

2. Use the tally table to create a time-table with a start and end time that spans 5 minute increments:

SELECT DATEADD(minute, n - 5, CAST(CAST(GETDATE() AS DATE) AS DATETIME)) AS StartTime,

DATEADD(millisecond, n * 60000 - 3, CAST(CAST(GETDATE() AS DATE) AS DATETIME)) AS EndTime

FROM DBA.dbo.tally

WHERE n > 0

AND n % 5 = 0

AND n <= 1440;

3. Use the time-table created in step 2 to join to the Watson table to group events into 5 minute buckets.