Under a new state law, Tennessee retailers will have to charge smokers at least 15 percent more than the wholesale cost. The surcharge is theirs to keep. That increase follows last year’s law requiring wine to be sold at least 20 percent above cost and another longstanding law requiring a 10 percent markup on milk. Justin Owen, the head of the conservative Beacon Center, calls those markups a “hidden tax increase” – except that the proceeds are funneled to retailers.