Thanks Florian, I did try that however my min/max/step had to be dynamic. I was writing a response to your post and got thinking of this and came up with a solution using the min/max/step as you suggested however using an expression to calculate the values.
One of the issues was that the figures for the expression in the image I posted can change and therefore the min/max values change and the number of steps would change. Another problem I had was that I had other expressions in the same chart that where hidden with a conditional show and the min/max values for these where also completely different.
Thanks for your response anyhow as it made me think a bit more about what I was doing.