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 $216.49   9.765%   $237.6302   $237.63   $237.65   $237.60  
  Purchase #2 $168.91   3.413%   $174.6749   $174.67   $174.65   $174.70  
  Purchase #3 $30.87   9.299%   $33.7406   $33.74   $33.75   $33.70  
  Purchase #4 $16.61   9.822%   $18.2414   $18.24   $18.25   $18.20  
  Purchase #5 $54.89   11.580%   $61.2463   $61.25   $61.25   $61.20  
  Purchase #6 $69.53   11.606%   $77.5997   $77.60   $77.60   $77.60  
  Purchase #7 $95.67   3.208%   $98.7391   $98.74   $98.75   $98.70  
  7 purchase totals = $652.97       $701.8722   $701.87   $701.90   $701.70