62:6 A shopkeeper is allowed to distribute things like nuts to children in order to accustom them to buy from his store. One may likewise sell items at below the going rate in order to encourage business; the other merchants have no legal right to stop one from doing so.
62:7 One who measures or weighs less than he should to any customer - Jewish or non-Jewish - violates a negative commandment: Don't act unjustly...in measuring, in weighing or in volume'' (Leviticus 19:35). The Divine punishment for using inaccurate weights and measures is particularly severe since it is impossible for the one who uses them to completely make good on his deception. The seller has no way of knowing whom he has shorted how much money, so he can never fully correct his misdeed. Even if he involves himself in the needs of the community, it is not considered a complete repentance.