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 $68.64   10.752%   $76.0202   $76.02   $76.00   $76.00  
  Purchase #2 $229.71   6.258%   $244.0853   $244.09   $244.10   $244.10  
  Purchase #3 $91.64   8.540%   $99.4661   $99.47   $99.45   $99.50  
  Purchase #4 $62.98   13.551%   $71.5144   $71.51   $71.50   $71.50  
  Purchase #5 $106.99   7.189%   $114.6815   $114.68   $114.70   $114.70  
  Purchase #6 $184.89   5.679%   $195.3899   $195.39   $195.40   $195.40  
  Purchase #7 $83.55   12.611%   $94.0865   $94.09   $94.10   $94.10  
  7 purchase totals = $828.40       $895.2439   $895.25   $895.25   $895.30