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 $172.36   13.443%   $195.5304   $195.53   $195.55   $195.50  
  Purchase #2 $68.55   5.731%   $72.4786   $72.48   $72.50   $72.50  
  Purchase #3 $12.62   10.577%   $13.9548   $13.95   $13.95   $14.00  
  Purchase #4 $129.69   4.251%   $135.2031   $135.20   $135.20   $135.20  
  Purchase #5 $44.87   4.869%   $47.0547   $47.05   $47.05   $47.10  
  Purchase #6 $242.82   11.237%   $270.1057   $270.11   $270.10   $270.10  
  Purchase #7 $58.61   5.788%   $62.0023   $62.00   $62.00   $62.00  
  7 purchase totals = $729.52       $796.3296   $796.32   $796.35   $796.40