Does Google Round Review Ratings Up or Down?

Google rounds your average to the nearest single decimal place using standard rounding. An average of 4.44 shows as 4.4; 4.45 rounds up to 4.5; 4.46 also shows as 4.5.

This matters when you are close to a threshold: you do not need a perfect 4.5 average to display 4.5, you only need to cross 4.45. That last stretch is often just a few more five-star reviews.