specials

Good day. I would like to query from Makro how exactly their specials work since we only bought their R100 specials and we took a calculater with and every item was rounded off we got a figure and as we got to the, our figure came to R4600 and the till i was like a thousand rand difference which their figure came to R5600, after the so called specials were taken off it was still more then what we calculated and it was R5053.. I would like Makro to explain why their is still a differnce of about R400 and is those specials a **** or what exactly is going on? we kept the receipt and is more then willing to go into the Makro store if they are willing to assist us with our query.