TheStreet's Jim Cramer says Dollar General (DG) knows the power of monthly sales numbers, even though most retailers have stopped reporting monthly numbers. Cramer notes that Dollar General's top line and bottom line were disappointing, but they reported April was better and May is continuing to improve. Cramer says the progression of positive numbers is getting investors excited. Dollar General received two downgrades last week even though Goldman Sachs recommended the company earlier. Cramer says consumers are still trading down and shopping at Dollar General. Cramer advises investors to stay away from Walmart (WMT) and he is looking at Target (TGT) because of its dividend, but dollar stores, and particularly Dollar General, still work.