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 $87.71   8.627%   $95.2767   $95.28   $95.30   $95.30  
  Purchase #2 $95.63   6.248%   $101.605   $101.61   $101.60   $101.60  
  Purchase #3 $157.97   3.689%   $163.7975   $163.80   $163.80   $163.80  
  Purchase #4 $214.86   10.305%   $237.0013   $237.00   $237.00   $237.00  
  Purchase #5 $116.33   13.615%   $132.1683   $132.17   $132.15   $132.20  
  Purchase #6 $120.40   13.447%   $136.5902   $136.59   $136.60   $136.60  
  Purchase #7 $218.91   13.230%   $247.8718   $247.87   $247.85   $247.90  
  7 purchase totals = $1,011.81       $1,114.3108   $1,114.32   $1,114.30   $1,114.40