Say for example I have a graph where the important y values are between 50 and 150 and I want the major tick marks at multiples of 50 and the minor at multiples of 10. But I might have some values that go right up to the edge, so to give a little visual padding I want to make the range from 30-170. How do I set up my ticks so they still fall on multiples of 50, and the first tick is a minor instead of a major?