Unfortunately, this happens to me every single time I shop at Walmart. There will be several items which ring up at a higher price than what is on the shelf label (and yes, I verify the label with the product before I take it). I normally use the self-checkout register so that I can monitor the prices more easily. I then have to get the SCO Cashier to come over and make the correction.
One time, I had a product that was $1.97; however, it rang up at $1.98. I had 3 of these items. I had to get the SCO Cashier to correct the price - I even showed her the sign with the price, as it was on an end-cap clearly visible from where we were located. She laughed and told me "that's only 1¢"! I told her "Yes, but that's 3 items so it's 3¢, and that's MY 3¢, not Walmart's." (Yes, 3¢ is not much, but when everyone purchasing this is charge the same extra 1¢, then that takes more money out of our pockets and puts it into Walmart's pocket.) If this was the only time this happened, then I would not have worried about it; but this happens all of the time.
Sometimes I have also had them doubt my claim of the price. I then request they get a Price Check - and after waiting a bit, they ultimately come back with the price I told them, and I get the items for that price. (However, I did have one time where they came back with a different price. I did NOT buy the item, because I knew the price was marked for what I told them. After paying for my other items, I went back to the shelf and found the sign had been changed; the associate in the dept knew what I was looking for and told me that she requested the sign be changed!!!)
I also have had instances where the Cashier refused to get a Price Check verification; they just tell me "that's the price it is on the register, so I can't do anything about it." In those cases, I make them VOID the item and I do NOT BUY IT. This results in lost Sales for Walmart!