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 $60.26   3.553%   $62.401   $62.40   $62.40   $62.40  
  Purchase #2 $173.75   11.334%   $193.4428   $193.44   $193.45   $193.40  
  Purchase #3 $183.58   13.782%   $208.881   $208.88   $208.90   $208.90  
  Purchase #4 $236.36   12.736%   $266.4628   $266.46   $266.45   $266.50  
  Purchase #5 $89.96   8.181%   $97.3196   $97.32   $97.30   $97.30  
  Purchase #6 $114.38   7.668%   $123.1507   $123.15   $123.15   $123.20  
  Purchase #7 $239.93   9.338%   $262.3347   $262.33   $262.35   $262.30  
  7 purchase totals = $1,098.22       $1,213.9926   $1,213.98   $1,214.00   $1,214.00