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 $214.61   5.356%   $226.1045   $226.10   $226.10   $226.10  
  Purchase #2 $235.61   5.515%   $248.6039   $248.60   $248.60   $248.60  
  Purchase #3 $137.27   5.335%   $144.5934   $144.59   $144.60   $144.60  
  Purchase #4 $118.63   5.213%   $124.8142   $124.81   $124.80   $124.80  
  Purchase #5 $163.53   5.687%   $172.83   $172.83   $172.85   $172.80  
  Purchase #6 $179.95   8.773%   $195.737   $195.74   $195.75   $195.70  
  Purchase #7 $162.83   4.164%   $169.6102   $169.61   $169.60   $169.60  
  7 purchase totals = $1,212.43       $1,282.2932   $1,282.28   $1,282.30   $1,282.20