I agree with CC. here at Almacenes Iberia I had to do it countless times, to go look for a sticker etc. I have a good memory and when the products are passed by the IR reader at the register, and the wrong price pops up, I make an issue out of that and demand the correct price be charged. Usually if I have time, I even haggle about couple of pesos, these people won't take me for stupid and charge wrong price when advertised differently. It is true most dominicans don't check receipts at cash register, nor pay attention of what is being charged. Also, same as CC I sometimes use cellphone calculator to compare price/volume ratios. It's incredible what results you can see sometimes.