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 $41.73   11.526%   $46.5398   $46.54   $46.55   $46.50  
  Purchase #2 $149.59   3.127%   $154.2677   $154.27   $154.25   $154.30  
  Purchase #3 $248.65   11.159%   $276.3969   $276.40   $276.40   $276.40  
  Purchase #4 $158.26   11.781%   $176.9046   $176.90   $176.90   $176.90  
  Purchase #5 $23.28   11.426%   $25.94   $25.94   $25.95   $25.90  
  Purchase #6 $169.97   9.398%   $185.9438   $185.94   $185.95   $185.90  
  Purchase #7 $130.58   13.454%   $148.1482   $148.15   $148.15   $148.10  
  7 purchase totals = $922.06       $1,014.1410   $1,014.14   $1,014.15   $1,014.00