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 $43.95   6.109%   $46.6349   $46.63   $46.65   $46.60  
  Purchase #2 $103.76   12.444%   $116.6719   $116.67   $116.65   $116.70  
  Purchase #3 $80.61   5.445%   $84.9992   $85.00   $85.00   $85.00  
  Purchase #4 $245.70   6.569%   $261.84   $261.84   $261.85   $261.80  
  Purchase #5 $199.36   5.336%   $209.9978   $210.00   $210.00   $210.00  
  Purchase #6 $234.69   11.620%   $261.961   $261.96   $261.95   $262.00  
  Purchase #7 $162.86   11.279%   $181.229   $181.23   $181.25   $181.20  
  7 purchase totals = $1,070.93       $1,163.3338   $1,163.33   $1,163.35   $1,163.30