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 $62.95   11.829%   $70.3964   $70.40   $70.40   $70.40  
  Purchase #2 $233.53   11.802%   $261.0912   $261.09   $261.10   $261.10  
  Purchase #3 $227.26   12.710%   $256.1447   $256.14   $256.15   $256.10  
  Purchase #4 $250.72   6.463%   $266.924   $266.92   $266.90   $266.90  
  Purchase #5 $246.38   5.182%   $259.1474   $259.15   $259.15   $259.10  
  Purchase #6 $228.64   4.852%   $239.7336   $239.73   $239.75   $239.70  
  Purchase #7 $101.36   13.133%   $114.6716   $114.67   $114.65   $114.70  
  7 purchase totals = $1,350.84       $1,468.1089   $1,468.10   $1,468.10   $1,468.00