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 $92.75   3.462%   $95.961   $95.96   $95.95   $96.00  
  Purchase #2 $179.36   10.756%   $198.652   $198.65   $198.65   $198.70  
  Purchase #3 $37.35   7.759%   $40.248   $40.25   $40.25   $40.20  
  Purchase #4 $148.81   9.505%   $162.9544   $162.95   $162.95   $163.00  
  Purchase #5 $186.37   12.354%   $209.3941   $209.39   $209.40   $209.40  
  Purchase #6 $119.82   8.169%   $129.6081   $129.61   $129.60   $129.60  
  Purchase #7 $208.49   13.711%   $237.0761   $237.08   $237.10   $237.10  
  7 purchase totals = $972.95       $1,073.8937   $1,073.89   $1,073.90   $1,074.00