If your intentions are to actually displaying hex 0 to 9 on an LCD, you might just have a look up table where 0 = 30h, 1 = 31h....etc. So when you want the LCD to display the register contents, do the conversion using the lookup table & then the result is sent to the LCD. So if your hex value was 9, the lookup table will show 39h. If 39H is sent to the LCD, it will appear to a user as number 9.