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 $92.26   3.216%   $95.2271   $95.23   $95.25   $95.20  
  Purchase #2 $51.56   10.754%   $57.1048   $57.10   $57.10   $57.10  
  Purchase #3 $234.76   9.226%   $256.419   $256.42   $256.40   $256.40  
  Purchase #4 $239.34   9.317%   $261.6393   $261.64   $261.65   $261.60  
  Purchase #5 $19.78   8.308%   $21.4233   $21.42   $21.40   $21.40  
  Purchase #6 $247.50   5.862%   $262.0085   $262.01   $262.00   $262.00  
  Purchase #7 $224.88   10.704%   $248.9512   $248.95   $248.95   $249.00  
  7 purchase totals = $1,110.08       $1,202.7732   $1,202.77   $1,202.75   $1,202.70