import json 

def reduce_coordinate_precision(geojson_data, precision=5):
    """Reduces the decimal precision of coordinates in GeoJSON data."""
    features = geojson_data.get('features', [])
    for feature in features:
        if feature['geometry']['type'] == 'Polygon':
            coords = feature['geometry']['coordinates']
            rounded_coords = [[[round(coord, precision) for coord in point] for point in ring] for ring in coords]
            feature['geometry']['coordinates'] = rounded_coords

    return geojson_data