Let's do some math ..  Rounding examples of 10 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $59.43   3.290%   $61.3852   $61.39   $61.40   $61.40  
  Purchase #2 $224.95   12.394%   $252.8303   $252.83   $252.85   $252.80  
  Purchase #3 $187.99   5.571%   $198.4629   $198.46   $198.45   $198.50  
  Purchase #4 $144.51   7.788%   $155.7644   $155.76   $155.75   $155.80  
  Purchase #5 $208.45   12.800%   $235.1316   $235.13   $235.15   $235.10  
  Purchase #6 $120.75   8.539%   $131.0608   $131.06   $131.05   $131.10  
  Purchase #7 $174.99   11.200%   $194.5889   $194.59   $194.60   $194.60  
  Purchase #8 $9.25   9.853%   $10.1614   $10.16   $10.15   $10.20  
  Purchase #9 $174.76   6.784%   $186.6157   $186.62   $186.60   $186.60  
  Purchase #10 $77.91   11.289%   $86.7053   $86.71   $86.70   $86.70  
  10 purchase totals = $1,382.99       $1,512.7065   $1,512.71   $1,512.70   $1,512.80  
Come on folks.. this just does not make any cents. We got rid of the 1/2 cent back in 1857.. Getting rid of the 1 cent coin is way, WAY past due. The penny has become a social and cultural anachronism. If our friends in Canada, Australia and a dozen other countries can stop the use of their pennies, why can't we?