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 $94.26   3.572%   $97.627   $97.63   $97.65   $97.60  
  Purchase #2 $195.66   11.228%   $217.6287   $217.63   $217.65   $217.60  
  Purchase #3 $8.96   8.193%   $9.6941   $9.69   $9.70   $9.70  
  Purchase #4 $85.78   10.248%   $94.5707   $94.57   $94.55   $94.60  
  Purchase #5 $116.25   5.754%   $122.939   $122.94   $122.95   $122.90  
  Purchase #6 $178.41   7.639%   $192.0387   $192.04   $192.05   $192.00  
  Purchase #7 $23.70   5.745%   $25.0616   $25.06   $25.05   $25.10  
  7 purchase totals = $703.02       $759.5598   $759.56   $759.60   $759.50