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 $59.95   3.416%   $61.9979   $62.00   $62.00   $62.00  
  Purchase #2 $162.35   13.180%   $183.7477   $183.75   $183.75   $183.70  
  Purchase #3 $218.41   6.712%   $233.0697   $233.07   $233.05   $233.10  
  Purchase #4 $21.75   8.630%   $23.627   $23.63   $23.65   $23.60  
  Purchase #5 $102.41   11.551%   $114.2394   $114.24   $114.25   $114.20  
  Purchase #6 $94.88   9.526%   $103.9183   $103.92   $103.90   $103.90  
  Purchase #7 $156.47   11.504%   $174.4703   $174.47   $174.45   $174.50  
  7 purchase totals = $816.22       $895.0703   $895.08   $895.05   $895.00