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 $186.52   4.627%   $195.1503   $195.15   $195.15   $195.20  
  Purchase #2 $214.52   10.182%   $236.3624   $236.36   $236.35   $236.40  
  Purchase #3 $79.29   9.616%   $86.9145   $86.91   $86.90   $86.90  
  Purchase #4 $35.88   5.229%   $37.7562   $37.76   $37.75   $37.80  
  Purchase #5 $207.83   4.423%   $217.0223   $217.02   $217.00   $217.00  
  Purchase #6 $54.90   10.222%   $60.5119   $60.51   $60.50   $60.50  
  Purchase #7 $247.88   5.360%   $261.1664   $261.17   $261.15   $261.20  
  7 purchase totals = $1,026.82       $1,094.8840   $1,094.88   $1,094.80   $1,095.00