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 $58.49   8.569%   $63.502   $63.50   $63.50   $63.50  
  Purchase #2 $195.86   6.522%   $208.634   $208.63   $208.65   $208.60  
  Purchase #3 $13.56   8.516%   $14.7148   $14.71   $14.70   $14.70  
  Purchase #4 $225.95   3.294%   $233.3928   $233.39   $233.40   $233.40  
  Purchase #5 $200.68   6.482%   $213.6881   $213.69   $213.70   $213.70  
  Purchase #6 $239.39   5.709%   $253.0568   $253.06   $253.05   $253.10  
  Purchase #7 $190.94   4.511%   $199.5533   $199.55   $199.55   $199.60  
  7 purchase totals = $1,124.87       $1,186.5418   $1,186.53   $1,186.55   $1,186.60