Slightly modified Dwain code to return exactly what OP has asked:

DECLARE @t TABLE (strcol CHAR(3));

DECLARE @ValueOfInterest INT = 10;

INSERT INTO @t (strcol)

SELECT ' 5' UNION ALL SELECT ' 6' UNION ALL SELECT ' 3'

UNION ALL SELECT ' 4' UNION ALL SELECT ' 3';

-- Improved Combinations

;WITH UNIQUEnTuples (n, Tuples, ID, CSum) AS (

SELECT DISTINCT 1, CAST(strcol AS VARCHAR(8000)), strcol, CAST(strcol AS INT)

FROM @t

UNION ALL

SELECT 1 + n.n, t.strcol + ',' + n.Tuples, strcol, CSum+CAST(t.strcol AS INT)

FROM UNIQUEnTuples n

CROSS APPLY (

SELECT strcol

FROM @t t

WHERE t.strcol < n.ID) t

)

SELECT DISTINCT Tuples, SumOfTuples=CSum

FROM UNIQUEnTuples

WHERE n <= 2 AND CSum = (SELECT MAX(CSum) MS

FROM UNIQUEnTuples

WHERE n <= 2 AND CSum < @ValueOfInterest)

ORDER BY CSum DESC;