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 $44.73   7.163%   $47.934   $47.93   $47.95   $47.90  
  Purchase #2 $244.92   7.253%   $262.684   $262.68   $262.70   $262.70  
  Purchase #3 $54.89   4.399%   $57.3046   $57.30   $57.30   $57.30  
  Purchase #4 $14.37   8.385%   $15.5749   $15.57   $15.55   $15.60  
  Purchase #5 $217.76   8.160%   $235.5292   $235.53   $235.55   $235.50  
  Purchase #6 $160.63   7.428%   $172.5616   $172.56   $172.55   $172.60  
  Purchase #7 $146.83   11.856%   $164.2382   $164.24   $164.25   $164.20  
  7 purchase totals = $884.13       $955.8265   $955.81   $955.85   $955.80