Costs according to the full route distance instead of assigning costs to edges

[sharvanc]

In the case of a custom cost structure that varies in slabs with the round trip distance of the whole route. For example, a cost structure like the following:

Round trip distance	Cost
> 400 KMs	$ 3 / KM
301 - 400 KMs	$1000
201 - 300 KMs	$ 800
101 - 200 KMs	$ 600
0 - 100 KMs	$ 400

Any way to implement something like this?