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 $176.88   3.395%   $182.8851   $182.89   $182.90   $182.90  
  Purchase #2 $232.54   12.874%   $262.4772   $262.48   $262.50   $262.50  
  Purchase #3 $188.81   9.719%   $207.1604   $207.16   $207.15   $207.20  
  Purchase #4 $44.36   5.688%   $46.8832   $46.88   $46.90   $46.90  
  Purchase #5 $223.45   12.415%   $251.1913   $251.19   $251.20   $251.20  
  Purchase #6 $85.72   12.724%   $96.627   $96.63   $96.65   $96.60  
  Purchase #7 $25.62   8.271%   $27.739   $27.74   $27.75   $27.70  
  7 purchase totals = $977.38       $1,074.9632   $1,074.97   $1,075.05   $1,075.00