I'm creating a lot of graphs, so I'm making a common scale to be able to compare them using MAX/MIN values that I'm hiding in the graph as a separate series. My Vertical AXIS (Y) is in units of 5.

The problem is that if my MAX is 27.5 then my scale in the graph is going to 35, and not 30. It always bumps up one extra 5. My data ranges (and space) demands I keep things tight, so: 

How do I amend my MAX/MIN values/series so it ROUNDS() to the next higher unit of 5?

How do I then limit the graph scale to the next **nearest** unit of 5? 

Hopefully it's not a manual thing with each graph.