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 $88.61   7.158%   $94.9527   $94.95   $94.95   $95.00  
  Purchase #2 $215.57   9.590%   $236.2432   $236.24   $236.25   $236.20  
  Purchase #3 $192.82   12.716%   $217.339   $217.34   $217.35   $217.30  
  Purchase #4 $100.26   13.483%   $113.7781   $113.78   $113.80   $113.80  
  Purchase #5 $15.89   8.495%   $17.2399   $17.24   $17.25   $17.20  
  Purchase #6 $224.51   4.139%   $233.8025   $233.80   $233.80   $233.80  
  Purchase #7 $67.97   5.434%   $71.6635   $71.66   $71.65   $71.70  
  7 purchase totals = $905.63       $985.0189   $985.01   $985.05   $985.00