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 $86.81   10.524%   $95.9459   $95.95   $95.95   $95.90  
  Purchase #2 $214.53   9.259%   $234.3933   $234.39   $234.40   $234.40  
  Purchase #3 $216.64   13.851%   $246.6468   $246.65   $246.65   $246.60  
  Purchase #4 $63.98   4.555%   $66.8943   $66.89   $66.90   $66.90  
  Purchase #5 $105.42   8.389%   $114.2637   $114.26   $114.25   $114.30  
  Purchase #6 $235.72   10.678%   $260.8902   $260.89   $260.90   $260.90  
  Purchase #7 $21.72   10.318%   $23.9611   $23.96   $23.95   $24.00  
  7 purchase totals = $944.82       $1,042.9953   $1,042.99   $1,043.00   $1,043.00