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 $206.54   5.330%   $217.5486   $217.55   $217.55   $217.50  
  Purchase #2 $14.67   4.809%   $15.3755   $15.38   $15.40   $15.40  
  Purchase #3 $72.46   5.405%   $76.3765   $76.38   $76.40   $76.40  
  Purchase #4 $116.85   4.577%   $122.1982   $122.20   $122.20   $122.20  
  Purchase #5 $215.51   7.380%   $231.4146   $231.41   $231.40   $231.40  
  Purchase #6 $161.87   8.744%   $176.0239   $176.02   $176.00   $176.00  
  Purchase #7 $223.44   5.840%   $236.4889   $236.49   $236.50   $236.50  
  7 purchase totals = $1,011.34       $1,075.4262   $1,075.43   $1,075.45   $1,075.40