Remember when Xbox LIVE was young, and the only available point values to purchase were 500, 1000 , etc? Those values were strange, because they didn't match the cost of the games and you always had strange leftover amounts. On a $5 (400) game, you had 100 leftover useless MSPoints (which is approximate $1.50). On a $10 (800) game, you had 200 unused MSPoints leftover. Not enough to do anything with, but no refunds on your real-life money.