A little late to this discussion, but here goes anyway. Mt. SAC used to be done with handtiming, and as with most cross country meets, the 10ths were dropped and the time was recorded in whole seconds. The shift to electronic timing was somewhere in the early '90's, and when Milena Glusac of Fallbrook ran a great time, it was decided to drop the 10ths off the electronic time as well to provide a comparison with the hand times from before.

The issue of rounding up to the nearest even 10th came from the stopwatches of the day, which were geared towards horse racing. These races were traditionally timed in 5ths, so human times were recorded in 5ths as well.