(When the fixes are part of the approach procedure IAF - IF - FAF)
If the step-down altitudes and the glide path intercept alt are (at) altitudes then you have to cross all the fixes and the GPIP at these altitudes. If the controller wants you to leave 5000ft on the ILS glide slope for whatever reason he has to state this specifically in the approach clearance.
If the altitudes are specified (at or above) then you are free to leave 5000ft on the ILS GS or fly the procedure as above or anything in between. Again, if the controller wants you to leave 5000ft on the ILS GS he has to include this in the approach clearance.