Force Y-Axis labels on Bar-Chart to be integers (no decimal places)

I have bar-chart, I would like to specify that the Y-Axis numbers must be integer - the values in the chart are children born per day, obviously you cannot have half a child born, so the Y-Axis should be integers. The Unit field selected is Number. When I set the Decimals to 0 and save, it is ignored and it reverts to 1. How can I force the Y-Axis to have integer labels only.