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 $59.41   7.105%   $63.6311   $63.63   $63.65   $63.60  
  Purchase #2 $250.38   7.611%   $269.4364   $269.44   $269.45   $269.40  
  Purchase #3 $65.70   8.633%   $71.3719   $71.37   $71.35   $71.40  
  Purchase #4 $212.41   11.521%   $236.8818   $236.88   $236.90   $236.90  
  Purchase #5 $95.57   6.298%   $101.589   $101.59   $101.60   $101.60  
  Purchase #6 $217.99   12.491%   $245.2191   $245.22   $245.20   $245.20  
  Purchase #7 $166.38   4.726%   $174.2431   $174.24   $174.25   $174.20  
  7 purchase totals = $1,067.84       $1,162.3724   $1,162.37   $1,162.40   $1,162.30