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 $88.38   7.451%   $94.9652   $94.97   $94.95   $95.00  
  Purchase #2 $178.98   9.633%   $196.2211   $196.22   $196.20   $196.20  
  Purchase #3 $26.82   10.553%   $29.6503   $29.65   $29.65   $29.70  
  Purchase #4 $63.99   5.499%   $67.5088   $67.51   $67.50   $67.50  
  Purchase #5 $156.37   9.383%   $171.0422   $171.04   $171.05   $171.00  
  Purchase #6 $209.73   13.121%   $237.2487   $237.25   $237.25   $237.20  
  Purchase #7 $217.46   6.571%   $231.7493   $231.75   $231.75   $231.70  
  7 purchase totals = $941.73       $1,028.3856   $1,028.39   $1,028.35   $1,028.30