--Once again, I'll build your test data first
DECLARE @TABLE AS TABLE(
[RequestID] INT,
[RequestItemID] INT,
[CostLocal] FLOAT,
[Qty] INT,
[Total_doller] FLOAT)

INSERT INTO @TABLE([RequestID],[RequestItemID],[CostLocal],[Qty],[Total_doller])
SELECT 331, 1036, 123.0000, 2, 5.05776
UNION ALL SELECT 331, 1037, 100.0000, 3, 6.168

--Now to the query
SELECT [RequestID],
       SUM([Total_doller]) AS [Total]
FROM   @TABLE
GROUP  BY [RequestID]

/*
RequestID   Total
----------- ----------------------
331         11.22576
*/