With various local fiat currencies that use the cent model.
I remember I once met a person who got confused between American cents, Australian cents and Euro cents. Strange guy, never met another person like that
Sure, that's uncommon; but that's because there are not many people that are exposed to more than one monetary system that uses cents. If bitcoin were to adopt a cent model, there would be a lot more of such confusion wherever cents are the local fiat model. It'd be much better to use the mills system mentioned earlier, since it's no longer in common use otherwise.