You will need a varchar column to hold this data - you cannot store it in a numeric column. So it would be something like this:
-- first add the salary indicator column.
ALTER TABLE YourTable ADD SalaryIndicator VARCHAR(32);
-- now populate the column. You could even make this a computed column
UPDATE YourTable SET SalaryIndicator
= CAST(ROUND(Salary,-3)/1000 AS VARCHAR(32)) + ' *';