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 $84.69   12.223%   $95.0417   $95.04   $95.05   $95.00  
  Purchase #2 $115.86   4.438%   $121.0019   $121.00   $121.00   $121.00  
  Purchase #3 $173.60   12.851%   $195.9093   $195.91   $195.90   $195.90  
  Purchase #4 $191.41   13.302%   $216.8714   $216.87   $216.85   $216.90  
  Purchase #5 $206.27   13.440%   $233.9927   $233.99   $234.00   $234.00  
  Purchase #6 $248.97   5.105%   $261.6799   $261.68   $261.70   $261.70  
  Purchase #7 $46.52   11.666%   $51.947   $51.95   $51.95   $51.90  
  7 purchase totals = $1,067.32       $1,176.4439   $1,176.44   $1,176.45   $1,176.40