Question for Jumbo Riche Terre

Went to do shopping in the supermarket , 5 item i took was mention the article at low price , when going to the cashier all the 5 items price are different around 30 rupees more than the advertised price, why so?, and how many people are paying more than expected , it's not good to do so , and the officer they cannot do anything need to pay the actual price that the cashier machine show