With due respect to all other posters in the countless threads on this topic, there is no definitive answer to your question.
If you read all of the responses, some say they've adjusted by a half size, and some say their regular size has worked just fine. (I'm in the latter group.)
Your best guess is probably your best answer—meaning that if you're sorta in between sizes, you might try the half size smaller, and if you're one of those people who always wears the same size in every shoe you own (both tennis and street shoes), you might be better off sticking with your normal size.
If you buy from a major online retailer, you can buy both and return the size that doesn't fit. A lot of posters have tried that.
Good luck. Just remember, we're all different.