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 $189.27   5.808%   $200.2628   $200.26   $200.25   $200.30  
  Purchase #2 $68.34   9.356%   $74.7339   $74.73   $74.75   $74.70  
  Purchase #3 $216.35   9.242%   $236.3451   $236.35   $236.35   $236.30  
  Purchase #4 $217.87   13.329%   $246.9099   $246.91   $246.90   $246.90  
  Purchase #5 $175.61   6.284%   $186.6453   $186.65   $186.65   $186.60  
  Purchase #6 $27.48   5.848%   $29.087   $29.09   $29.10   $29.10  
  Purchase #7 $117.81   3.248%   $121.6365   $121.64   $121.65   $121.60  
  7 purchase totals = $1,012.73       $1,095.6205   $1,095.63   $1,095.65   $1,095.50