The rules for the bounties make it clear that you cannot award your own answer. However it makes no reference to the automatic rewarding of half the amount to the highest scoring answer.
After the bounty ends, there is a grace period of 24 hours to manually award the bounty. Simply click the bounty award icon next to each answer to permanently award your bounty to the answerer. (You cannot award a bounty to your own answer.)
If you do not award your bounty within 7 days (plus the grace period), the highest voted answer created after the bounty started with a minimum score of 2 will be awarded half the bounty amount (or the full amount, if the answer is also accepted). If two or more eligible answers have the same score (their scores are tied), the oldest answer is chosen. If there's no answer meeting those criteria, no bounty is awarded to anyone.
The second paragraph reads as an "else" condition, it is the case when "you" do not award. It seems to imply that the automatic awarding can also choose your answer if it is the highest voted answer. Could this be rephrased to clearly state that your answer cannot receive any reputation at all irrespective of the outcome?