Have you thought about adding a simplification algorithm such as Ramer-Doublas-Peucker [0] or Visvalingam–Whyatt [1]? I've used https://mapshaper.org/ to do GeoJSON path simplification before and those seem to work very well. For applications which want to maintain path accuracy while reducing the number of waypoints that may be more effective than truncating the decimal places

[0] https://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93...

[1] https://en.wikipedia.org/wiki/Visvalingam%E2%80%93Whyatt_alg...