The management fee % set on the owner details screen in v8.9 will allow you to enter 4 decimal places.

For those that are interested, the current system will allow you to enter 4 decimal places, and it will then calculate the fees based on the 4 decimal place fee percent.  However if you later open the owner details screen again it will convert the fee percent back to 2 decimal places, which means when you save the owner the extra 2 decimal places is lost (unless you retype the 4 decimal places each time).