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 $58.90   8.205%   $63.7327   $63.73   $63.75   $63.70  
  Purchase #2 $241.53   8.349%   $261.6953   $261.70   $261.70   $261.70  
  Purchase #3 $129.94   13.169%   $147.0518   $147.05   $147.05   $147.10  
  Purchase #4 $114.69   8.548%   $124.4937   $124.49   $124.50   $124.50  
  Purchase #5 $208.38   5.491%   $219.8221   $219.82   $219.80   $219.80  
  Purchase #6 $108.43   10.844%   $120.1881   $120.19   $120.20   $120.20  
  Purchase #7 $107.72   8.840%   $117.2424   $117.24   $117.25   $117.20  
  7 purchase totals = $969.59       $1,054.2261   $1,054.22   $1,054.25   $1,054.20