Just use Round function

IF NOT OBJECT_ID('ANDRETEST') IS NULL

DROP TABLE ANDRETEST

GO

CREATE TABLE ANDRETEST

(

F1 FLOAT,

F2 CHAR(10)

)

GO

INSERT INTO ANDRETEST ( F1, F2 ) VALUES ( 160.2,'TEST')

INSERT INTO ANDRETEST ( F1, F2 ) VALUES ( 100,'TEST')

INSERT INTO ANDRETEST ( F1, F2 ) VALUES ( 79.5,'TEST')

SELECT ROUND(SUM(F1 - ROUND( F1, 0, 1)), 1) AS TEST FROM ANDRETEST

IF NOT OBJECT_ID('ANDRETEST') IS NULL

DROP TABLE ANDRETEST

GO