The majority of the time, sales that list items 10 for $10 DO NOT require shoppers to buy that number of items in order to get the discounted price. This is a clever marketing tool that stores use to increase sales, making the uninformed shopper think they have to buy the listed number of items to cash in on the low price. Also be on the lookout for other sales that make customers think they have to buy in sets (such as 2 for $5 or 3/$1, for example).
However, be sure to double check the fine print to make sure. Sometimes ads DO require shoppers buy a specific number of items to get the discounted price, but it will be very clearly listed in the ad. It will say something similar to “Must buy 5,” “Buy 10, save $5 instantly,” or “2 for $5 or single price $3.99 each.”