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 $200.62   6.705%   $214.0716   $214.07   $214.05   $214.10  
  Purchase #2 $244.53   9.129%   $266.8531   $266.85   $266.85   $266.90  
  Purchase #3 $208.97   8.173%   $226.0491   $226.05   $226.05   $226.00  
  Purchase #4 $178.70   3.192%   $184.4041   $184.40   $184.40   $184.40  
  Purchase #5 $131.85   9.551%   $144.443   $144.44   $144.45   $144.40  
  Purchase #6 $146.78   11.626%   $163.8446   $163.84   $163.85   $163.80  
  Purchase #7 $57.63   8.254%   $62.3868   $62.39   $62.40   $62.40  
  7 purchase totals = $1,169.08       $1,262.0523   $1,262.04   $1,262.05   $1,262.00