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 $119.65   5.826%   $126.6208   $126.62   $126.60   $126.60  
  Purchase #2 $108.27   6.295%   $115.0856   $115.09   $115.10   $115.10  
  Purchase #3 $234.91   6.383%   $249.9043   $249.90   $249.90   $249.90  
  Purchase #4 $209.46   4.795%   $219.5036   $219.50   $219.50   $219.50  
  Purchase #5 $48.37   4.706%   $50.6463   $50.65   $50.65   $50.60  
  Purchase #6 $207.75   6.472%   $221.1956   $221.20   $221.20   $221.20  
  Purchase #7 $197.82   7.384%   $212.427   $212.43   $212.45   $212.40  
  7 purchase totals = $1,126.23       $1,195.3832   $1,195.39   $1,195.40   $1,195.30