The Israeli supermarket chain is currently giving a 4nis rebate on every purchase. The rebate is the result of a class action suit that had been filed against Supersol, owners of the Yesh chain, for overcharging on products that were advertised as being on sale. The agreement arrived at to avoid the suit was that Yesh/Supersol would give back 8 million shekel to the public - 4 shekel on every purchase over 25nis.

The rebate program has already begun. Many people are trying to maximize their 4 shekel discount by breaking up their purchases into multiple purchases, qualifying for the 4 shekels each time, instead of just once on a larger purchase. This is commonly done to benefit in all sorts of ways - such as sales that put a limit on how many items you can buy at the discounted price, and the like.

Rav Yehuda Kanner, a rabbi in Modiin Ilit, pasked that one is not allowed to divide up one's purchases in this manner to benefit extra times from the discount. Doing so, Rav Kanner paskens, is theft.

According to Rav Kanner, the purpose of this arrangement is to give back money to the wider public and to pay the 4nis return to as many customers as possible, thus returning the overcharged monies to the public. Somebody dividing his purchases to obtain the 4nis discount multiple times on the same purchase, he says, is preventing the company from giving the money back to the public and from properly compensating the public. However, the caveat is, that you are not allowed to divide your purchase, but if you already did so, you do not have to return the money to anybody. 
source: Kikar