MajorUnit Property
Returns or sets the major units for the axis. Read/write Double.
Remarks
Setting this property sets the MajorUnitIsAuto property to False.
Use the TickMarkSpacing property to set tick-mark spacing on the category axis.
Example
This example sets the major and minor units for the value axis.
With myChart.Axes(xlValue)
.MajorUnit = 100
.MinorUnit = 20
End With