User can set AutoCalculateBounds to True by the following way:

 public class CustomClusterGenerator : DefaultClusterGenerator
    {
        public override ClusterData CreateCluster(Location center, object item)
        {
            var clusterData = base.CreateCluster(center, item);
            clusterData.AutoCalculateBounds = true;
            return clusterData;
        }
    }

  this.VisualizationLayer1.ClusterGenerator = new CustomClusterGenerator();

When clustering 4 points:

ObservableCollection<DataItem> items = new ObservableCollection<DataItem>()
            {
                new DataItem() {MapLocation = new Telerik.Windows.Controls.Map.Location(20, 30) },
                new DataItem() {MapLocation = new Telerik.Windows.Controls.Map.Location(20, 34) },

                new DataItem() {MapLocation = new Telerik.Windows.Controls.Map.Location(22, 32) },
                new DataItem() {MapLocation = new Telerik.Windows.Controls.Map.Location(18, 32) },
            };

            this.VisualizationLayer1.ItemsSource = items;

EXPECTED:  ClusterData's Bounds must  be:

WEST: 30 and EAST: 34.

Actual Values are 30 and 30 (29.9999 and 30).