DECLARE @Demo
TABLE   (
        data        DECIMAL(5,2) NOT NULL,
        odd_format  AS
                    CASE SIGN(data)
                        WHEN -1 THEN CONVERT(VARCHAR(7), data)
                        -- Assumes zero is 'positive'
                        ELSE '+' + CONVERT(VARCHAR(7), data)
                    END
                    PERSISTED NOT NULL
        );
        
INSERT  @Demo (data)
SELECT  TOP (20)
        CHECKSUM(NEWID()) % 99999 / 100.0
FROM    master.sys.all_columns;

SELECT  *
FROM    @Demo;