Here's a similar question, related to naming.
There's a local race that is one of the oldest in the state (49th running this year). Just for fun I measured it last year after the race and it came up about 70-80m short of its advertised 5 mile distance.
Now there is no way they are going to change this course after 49 years - too much history behind it (although to be honest, the finish on an old cinder track originally was run the opposite direction and MIGHT have been long enough).
My solution would be to omit any reference to the distance in the Race Name (just call it the so-and-so Memorial Day Race) and list the distance as 4.95 miles. The average runner is still going to call it "5 miles" but at least those who look it up will know the true distance.