What Exactly is x% Immunity Bonus?

[Vincent]

Could someone explain to me how these work?

ie, what happens if someone who has 5% Slashing Immunity Bonus gets hit with a scimitar?

[IDii]

5% of that damage is soaked by that immunity.

[Variable]

5% of the slashing damaged caused would not be counted.
    Edit: your to fast for me ; )

[Talan Va'lash]

An important thing to know is that it always rounds to at least 1.

hit for 40 - ignore 2
hit for 20 - ignore 1
hit for 10 - ignore 1
hit for 5 - ignore 1

so in most practical cases its 1/- damage resistance slashing