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 $214.85   4.141%   $223.7469   $223.75   $223.75   $223.70  
  Purchase #2 $237.92   11.495%   $265.2689   $265.27   $265.25   $265.30  
  Purchase #3 $161.29   6.509%   $171.7884   $171.79   $171.80   $171.80  
  Purchase #4 $46.49   11.294%   $51.7406   $51.74   $51.75   $51.70  
  Purchase #5 $44.84   7.444%   $48.1779   $48.18   $48.20   $48.20  
  Purchase #6 $55.56   13.725%   $63.1856   $63.19   $63.20   $63.20  
  Purchase #7 $195.27   6.565%   $208.0895   $208.09   $208.10   $208.10  
  7 purchase totals = $956.22       $1,031.9978   $1,032.01   $1,032.05   $1,032.00