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 $195.93   5.623%   $206.9471   $206.95   $206.95   $206.90  
  Purchase #2 $247.74   5.546%   $261.4797   $261.48   $261.50   $261.50  
  Purchase #3 $63.82   9.559%   $69.9206   $69.92   $69.90   $69.90  
  Purchase #4 $239.66   12.296%   $269.1286   $269.13   $269.15   $269.10  
  Purchase #5 $220.62   12.686%   $248.6079   $248.61   $248.60   $248.60  
  Purchase #6 $244.66   5.454%   $258.0038   $258.00   $258.00   $258.00  
  Purchase #7 $142.61   3.808%   $148.0406   $148.04   $148.05   $148.00  
  7 purchase totals = $1,355.04       $1,462.1283   $1,462.13   $1,462.15   $1,462.00