You have only shared a small piece of your code, so we need to guess.
Is your code selecting into a table? i.e. Maybe the following code example will show what I mean.
CREATE TABLE #Test (Value DECIMAL(15, 12));
INSERT INTO #Test VALUES (123.759815009);
SELECT * FROM #Test;
DROP TABLE #Test;
GO
CREATE TABLE #Test (Value DECIMAL(15, 12));
INSERT INTO #Test VALUES (CAST(123.759815009 AS DECIMAL(10, 2)));
SELECT * FROM #Test;
DROP TABLE #Test;
GO
CREATE TABLE #Test (Value DECIMAL(10, 2));
INSERT INTO #Test VALUES (123.759815009);
SELECT * FROM #Test;
DROP TABLE #Test;
GO
