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 $243.54   7.571%   $261.9784   $261.98   $262.00   $262.00  
  Purchase #2 $136.77   3.300%   $141.2834   $141.28   $141.30   $141.30  
  Purchase #3 $23.44   3.609%   $24.2859   $24.29   $24.30   $24.30  
  Purchase #4 $152.54   3.175%   $157.3831   $157.38   $157.40   $157.40  
  Purchase #5 $206.52   13.375%   $234.1421   $234.14   $234.15   $234.10  
  Purchase #6 $139.31   3.561%   $144.2708   $144.27   $144.25   $144.30  
  Purchase #7 $208.25   10.858%   $230.8618   $230.86   $230.85   $230.90  
  7 purchase totals = $1,110.37       $1,194.2055   $1,194.20   $1,194.25   $1,194.30