reporting services - Custom interval expression for the Vertical Axis Major Tick Marks in SSRS 2008 R2 -

i creating chart in business intelligence development studio ssrs 2008 r2. having issue vertical axis major tick marks. when left on auto, sets major tick marks @ every 2 million. wanting them every 1 million. how go creating expression accomplish this?

i able adjusted setting maximum value to:

sum of y-axis field plus 1,000,000.