My son was wearing toddler shoe sizes (5, 6, 7 and 8), but now that he's starting to outgrow his size 8, I need to buy him a pair in the regular kid sizes. However, I noticed the kid sizes come in half sizes, so the next size would be 8.5 followed by 9, 9.5, 10, etc. The difference in shoe length is only .3 inches between whole sizes and half that between half sizes. So is it necessary to buy a half size, or do most people keep moving up whole sizes?