Each 1/2 pt should be worth about 12 cents on halves. Where did you see it worth 40-50 cents? Remember that when a certain number results in a tie (which can't happen), then there are 3 numbers which are totally equivalent. For example if the HT score is 40-35 and you see the leading team for +5.5, +5 and +4.5 these are all equivalent because the game can't end in a tie.