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 $57.99   8.598%   $62.976   $62.98   $63.00   $63.00  
  Purchase #2 $185.38   11.438%   $206.5838   $206.58   $206.60   $206.60  
  Purchase #3 $101.87   10.189%   $112.2495   $112.25   $112.25   $112.20  
  Purchase #4 $248.99   5.606%   $262.9484   $262.95   $262.95   $262.90  
  Purchase #5 $169.34   13.640%   $192.438   $192.44   $192.45   $192.40  
  Purchase #6 $114.38   11.545%   $127.5852   $127.59   $127.60   $127.60  
  Purchase #7 $152.73   5.113%   $160.5391   $160.54   $160.55   $160.50  
  7 purchase totals = $1,030.68       $1,125.3200   $1,125.33   $1,125.40   $1,125.20