Percentage calculation error
 

I have an excel pie chart which calculates percent of total. When I set the
format to display one decimal point (ie. 65.8% and 34.2%) the numbers
displayed are accurate. However, when I change the format to display no
decimal points, the chart displays 65% and 34%. The 65.8% is not rounding up
to 66%. How do I correct the rounding on the chart?