Dollar General review: price gouging

I purchased a microfiber twist mop and the price said $11.00 w/ a $2.00 discount. when I checked out at the register I was charged $12.00 w/ a $2.00 discount.
When I informed the employee about the price listed on the product, she stated they didn't have a chance to change the price. But they had enough time to change it in the computer. Not only are they price gouging but they are also using false advertisement.
The store #04485.