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 $59.53   5.693%   $62.919   $62.92   $62.90   $62.90  
  Purchase #2 $240.81   3.124%   $248.3329   $248.33   $248.35   $248.30  
  Purchase #3 $184.32   11.836%   $206.1361   $206.14   $206.15   $206.10  
  Purchase #4 $187.57   7.837%   $202.2699   $202.27   $202.25   $202.30  
  Purchase #5 $222.37   12.117%   $249.3146   $249.31   $249.30   $249.30  
  Purchase #6 $217.34   12.475%   $244.4532   $244.45   $244.45   $244.50  
  Purchase #7 $208.75   11.749%   $233.276   $233.28   $233.30   $233.30  
  7 purchase totals = $1,320.69       $1,446.7017   $1,446.70   $1,446.70   $1,446.70