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 $59.28   5.840%   $62.742   $62.74   $62.75   $62.70  
  Purchase #2 $196.41   9.344%   $214.7626   $214.76   $214.75   $214.80  
  Purchase #3 $14.27   13.249%   $16.1606   $16.16   $16.15   $16.20  
  Purchase #4 $163.36   8.503%   $177.2505   $177.25   $177.25   $177.30  
  Purchase #5 $78.28   8.672%   $85.0684   $85.07   $85.05   $85.10  
  Purchase #6 $72.26   10.113%   $79.5677   $79.57   $79.55   $79.60  
  Purchase #7 $96.28   6.852%   $102.8771   $102.88   $102.90   $102.90  
  7 purchase totals = $680.14       $738.4289   $738.43   $738.40   $738.60