items not scanned and security haven't seen also

I was at Makro mbombela yesterday. I love to buy there because there is a lot of goods to purchase under one roof . When done shopping I went to a till to pay and offer to took out the heavy items out of the trolley. The cashier advise me to leave it in. Anyway, after paying I then headed to the exit, and cue in line at the security checkpoint. There the security just randomly stamping till slips without even checking them against the goods purchased. People just pushing forward in front of other people patiently waiting (including me) for their turn. The security was not even checking the slips, just randomly stamping them, and no effort was made to try and bring order to the exiting 'system'. Anyway to cut it short- I have checked the slip at home this morning when unpacking the goods, and some of the items haven't even been ringed up, because of cashier and security negligence at the store. I don't want to be imprisoned because the items haven't been paid for. Who need to take responsibility for that?