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 $72.61   5.566%   $76.6515   $76.65   $76.65   $76.70  
  Purchase #2 $195.39   4.426%   $204.038   $204.04   $204.05   $204.00  
  Purchase #3 $222.56   12.188%   $249.6856   $249.69   $249.70   $249.70  
  Purchase #4 $28.38   5.467%   $29.9315   $29.93   $29.95   $29.90  
  Purchase #5 $80.58   3.685%   $83.5494   $83.55   $83.55   $83.50  
  Purchase #6 $17.31   6.224%   $18.3874   $18.39   $18.40   $18.40  
  Purchase #7 $207.62   12.522%   $233.6182   $233.62   $233.60   $233.60  
  7 purchase totals = $824.45       $895.8616   $895.87   $895.90   $895.80