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 $250.46   4.506%   $261.7457   $261.75   $261.75   $261.70  
  Purchase #2 $195.29   5.275%   $205.5915   $205.59   $205.60   $205.60  
  Purchase #3 $125.46   8.291%   $135.8619   $135.86   $135.85   $135.90  
  Purchase #4 $197.98   9.676%   $217.1365   $217.14   $217.15   $217.10  
  Purchase #5 $118.92   6.492%   $126.6403   $126.64   $126.65   $126.60  
  Purchase #6 $40.39   5.684%   $42.6858   $42.69   $42.70   $42.70  
  Purchase #7 $100.37   5.290%   $105.6796   $105.68   $105.70   $105.70  
  7 purchase totals = $1,028.87       $1,095.3413   $1,095.35   $1,095.40   $1,095.30