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 $46.92   10.729%   $51.954   $51.95   $51.95   $52.00  
  Purchase #2 $241.77   8.171%   $261.525   $261.53   $261.55   $261.50  
  Purchase #3 $225.27   4.553%   $235.5265   $235.53   $235.55   $235.50  
  Purchase #4 $140.80   9.757%   $154.5379   $154.54   $154.55   $154.50  
  Purchase #5 $107.66   9.240%   $117.6078   $117.61   $117.60   $117.60  
  Purchase #6 $216.78   8.171%   $234.4931   $234.49   $234.50   $234.50  
  Purchase #7 $116.89   3.819%   $121.354   $121.35   $121.35   $121.40  
  7 purchase totals = $1,096.09       $1,176.9983   $1,177.00   $1,177.05   $1,177.00