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 $58.81   5.467%   $62.0251   $62.03   $62.05   $62.00  
  Purchase #2 $119.44   8.538%   $129.6378   $129.64   $129.65   $129.60  
  Purchase #3 $130.59   3.697%   $135.4179   $135.42   $135.40   $135.40  
  Purchase #4 $80.99   13.712%   $92.0953   $92.10   $92.10   $92.10  
  Purchase #5 $104.76   6.855%   $111.9413   $111.94   $111.95   $111.90  
  Purchase #6 $7.26   9.249%   $7.9315   $7.93   $7.95   $7.90  
  Purchase #7 $202.37   6.865%   $216.2627   $216.26   $216.25   $216.30  
  7 purchase totals = $704.22       $755.3116   $755.32   $755.35   $755.20