Why is my examinee's age being rounded up in Woodcock-Johnson IV assessments?

An examinees' age will be rounded up to the nearest month if testing falls 15 days or later into the month. 

For example, when a student is tested and the test date happens to fall on the 16th day of the 
month, a 6-year 11-month-old examinee will be scored as a 7-year-old examinee.