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 $62.59   11.757%   $69.9487   $69.95   $69.95   $69.90  
  Purchase #2 $181.99   4.429%   $190.0503   $190.05   $190.05   $190.10  
  Purchase #3 $100.94   6.598%   $107.6   $107.60   $107.60   $107.60  
  Purchase #4 $249.37   8.458%   $270.4617   $270.46   $270.45   $270.50  
  Purchase #5 $81.94   4.443%   $85.5806   $85.58   $85.60   $85.60  
  Purchase #6 $148.25   5.185%   $155.9368   $155.94   $155.95   $155.90  
  Purchase #7 $230.31   6.217%   $244.6284   $244.63   $244.65   $244.60  
  7 purchase totals = $1,055.39       $1,124.2065   $1,124.21   $1,124.25   $1,124.20