Yeah, legend99 is spot on in the difference between the increments, as a result, US digital tuners won't be able to tune in exactly to some stations here. I believe the US bands are assigned on odd numbers after the point, i.e. 91.1, 91.3, 91.5, etc. Understandable US tuners will be designed to tune to these, most of RTE's output for example is on even numbers, 91.0, 91.2 etc.
I had a high-spec walkman years back that had a small switch inside the cover to switch between different increments. If it wasn't on the correct one, it was impossible to tune some stations properly.
Also, RDS is a European system, the US have RBDS, although I believe they are trying to harmonise the two.
Leo