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 $187.39   8.263%   $202.874   $202.87   $202.85   $202.90  
  Purchase #2 $215.52   10.696%   $238.572   $238.57   $238.55   $238.60  
  Purchase #3 $12.83   9.619%   $14.0641   $14.06   $14.05   $14.10  
  Purchase #4 $79.49   5.316%   $83.7157   $83.72   $83.70   $83.70  
  Purchase #5 $204.89   6.211%   $217.6157   $217.62   $217.60   $217.60  
  Purchase #6 $101.89   12.533%   $114.6599   $114.66   $114.65   $114.70  
  Purchase #7 $245.73   6.392%   $261.4371   $261.44   $261.45   $261.40  
  7 purchase totals = $1,047.74       $1,132.9385   $1,132.94   $1,132.85   $1,133.00