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 $244.49   7.153%   $261.9784   $261.98   $262.00   $262.00  
  Purchase #2 $176.99   7.456%   $190.1864   $190.19   $190.20   $190.20  
  Purchase #3 $59.78   3.729%   $62.0092   $62.01   $62.00   $62.00  
  Purchase #4 $140.71   9.603%   $154.2224   $154.22   $154.20   $154.20  
  Purchase #5 $180.96   5.351%   $190.6432   $190.64   $190.65   $190.60  
  Purchase #6 $153.72   7.789%   $165.6933   $165.69   $165.70   $165.70  
  Purchase #7 $40.41   6.567%   $43.0637   $43.06   $43.05   $43.10  
  7 purchase totals = $997.06       $1,067.7966   $1,067.79   $1,067.80   $1,067.80