(CNN) - Have you ever wondered how Dollar Tree is still able to continue selling everything in its stores for just a single dollar after all these years? According to one activist investor, it's because the store has lowered the value of the products it sells. In a sense, that’s right, as a static $1 price will, over time, effectively get cheaper and cheaper with inflation. That, at least, is according to Jeffrey Smith, the CEO of hedge fund Starboard Value. And he says it’s time for Dollar Tree to raise its prices.