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 $215.33   13.453%   $244.2983   $244.30   $244.30   $244.30  
  Purchase #2 $234.65   4.689%   $245.6527   $245.65   $245.65   $245.70  
  Purchase #3 $212.88   12.124%   $238.6896   $238.69   $238.70   $238.70  
  Purchase #4 $58.35   11.297%   $64.9418   $64.94   $64.95   $64.90  
  Purchase #5 $245.50   8.649%   $266.7333   $266.73   $266.75   $266.70  
  Purchase #6 $196.81   10.618%   $217.7073   $217.71   $217.70   $217.70  
  Purchase #7 $168.30   10.174%   $185.4228   $185.42   $185.40   $185.40  
  7 purchase totals = $1,331.82       $1,463.4458   $1,463.44   $1,463.45   $1,463.40