Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $86.82   9.410%   $94.9898   $94.99   $95.00   $95.00  
  Purchase #2 $61.38   9.165%   $67.0055   $67.01   $67.00   $67.00  
  Purchase #3 $48.25   4.524%   $50.4328   $50.43   $50.45   $50.40  
  Purchase #4 $79.87   7.546%   $85.897   $85.90   $85.90   $85.90  
  Purchase #5 $99.52   5.335%   $104.8294   $104.83   $104.85   $104.80  
  Purchase #6 $197.86   13.496%   $224.5632   $224.56   $224.55   $224.60  
  Purchase #7 $180.99   13.214%   $204.906   $204.91   $204.90   $204.90  
  7 purchase totals = $754.69       $832.6237   $832.63   $832.65   $832.60