I'm not sure which version this was changed in, but there seems to be a bug in Piratez_Globals.rul:
constants:
...
extendedMovementCostRounding: 1 #0-floor, 1-standard, 2-up
Both wrong value and wrongly
documented.
0 = Floor, 1 = Round(0.5 up), 2 = Round(0.5 down)
It should be set to 0 or 2, not 1.
0 is standard.