Check for awkward normals, fix if possible.

Select the polygons on one side, give it a particular smoothing group (say group 1)
select the opposite polygons, give it smoothing group 2

(following step, I'm assuming you're using gmax/Max)
select the leading edge polygons (where the two groups meet) and give those polygons smoothing group 3 (in essence, those polygons will have two smoothing groups) and give you a "smoothed rounded"  edge.

Hopefully....