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 $72.55   4.692%   $75.954   $75.95   $75.95   $76.00  
  Purchase #2 $227.52   3.745%   $236.0406   $236.04   $236.05   $236.00  
  Purchase #3 $186.42   4.330%   $194.492   $194.49   $194.50   $194.50  
  Purchase #4 $56.72   3.234%   $58.5543   $58.55   $58.55   $58.60  
  Purchase #5 $85.42   7.826%   $92.105   $92.11   $92.10   $92.10  
  Purchase #6 $201.89   3.381%   $208.7159   $208.72   $208.70   $208.70  
  Purchase #7 $53.62   12.862%   $60.5166   $60.52   $60.50   $60.50  
  7 purchase totals = $884.14       $926.3784   $926.38   $926.35   $926.40