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 $56.26   5.283%   $59.2322   $59.23   $59.25   $59.20  
  Purchase #2 $217.61   6.206%   $231.1149   $231.11   $231.10   $231.10  
  Purchase #3 $140.34   4.335%   $146.4237   $146.42   $146.40   $146.40  
  Purchase #4 $213.99   10.734%   $236.9597   $236.96   $236.95   $237.00  
  Purchase #5 $200.91   4.642%   $210.2362   $210.24   $210.25   $210.20  
  Purchase #6 $194.52   4.725%   $203.7111   $203.71   $203.70   $203.70  
  Purchase #7 $14.80   3.187%   $15.2717   $15.27   $15.25   $15.30  
  7 purchase totals = $1,038.43       $1,102.9495   $1,102.94   $1,102.90   $1,102.90