Target has had to tighten the reigns on their return policy due to return fraud and abuse. The 90 day window still remains for most items and Target brand items can still be returned up to a year. However, you will actually want to keep your physical or digital receipt handy if you think you may have to return the item, otherwise you may be denied the return.
It really shouldn't come as a surprise that retailers are rethinking the self-checkout philosophy. Retailers like Dollar General and Five Below have announced they were eliminating self-checkout due to the high rate of disappearing merchandise.