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 $195.71   5.774%   $207.0103   $207.01   $207.00   $207.00  
  Purchase #2 $247.92   9.574%   $271.6559   $271.66   $271.65   $271.70  
  Purchase #3 $23.80   13.647%   $27.048   $27.05   $27.05   $27.00  
  Purchase #4 $238.54   9.511%   $261.2275   $261.23   $261.25   $261.20  
  Purchase #5 $94.67   3.215%   $97.7136   $97.71   $97.70   $97.70  
  Purchase #6 $70.44   7.669%   $75.842   $75.84   $75.85   $75.80  
  Purchase #7 $207.76   7.439%   $223.2153   $223.22   $223.20   $223.20  
  7 purchase totals = $1,078.84       $1,163.7126   $1,163.72   $1,163.70   $1,163.60