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 $163.94   11.219%   $182.3324   $182.33   $182.35   $182.30  
  Purchase #2 $187.76   3.386%   $194.1176   $194.12   $194.10   $194.10  
  Purchase #3 $101.89   6.615%   $108.63   $108.63   $108.65   $108.60  
  Purchase #4 $50.99   3.477%   $52.7629   $52.76   $52.75   $52.80  
  Purchase #5 $212.25   4.147%   $221.052   $221.05   $221.05   $221.10  
  Purchase #6 $237.81   10.725%   $263.3151   $263.32   $263.30   $263.30  
  Purchase #7 $9.71   10.550%   $10.7344   $10.73   $10.75   $10.70  
  7 purchase totals = $964.35       $1,032.9444   $1,032.94   $1,032.95   $1,032.90