SQL Server - Round a number when it's one decimal before .50
If you want something other than a standard rounding, you will probably need to use a nested CASE statement.
Maybe take something like the below and tweak it:
DECLARE @Num DEC (10,2) = 8.49 --8.48 

SELECT 
CASE 
WHEN @Num - FLOOR(@Num) &gt;= 0.5 THEN ROUND(@Num,1)
WHEN @Num - FLOOR(@Num) = 0.49 THEN FLOOR(@Num) + 0.5 
ELSE @Num
END AS NewValue