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 $56.25   10.249%   $62.0151   $62.02   $62.00   $62.00  
  Purchase #2 $84.72   13.259%   $95.953   $95.95   $95.95   $96.00  
  Purchase #3 $192.33   8.630%   $208.9281   $208.93   $208.95   $208.90  
  Purchase #4 $227.34   4.525%   $237.6271   $237.63   $237.65   $237.60  
  Purchase #5 $201.63   3.851%   $209.3948   $209.39   $209.40   $209.40  
  Purchase #6 $144.68   3.396%   $149.5933   $149.59   $149.60   $149.60  
  Purchase #7 $79.96   12.610%   $90.043   $90.04   $90.05   $90.00  
  7 purchase totals = $986.91       $1,053.5544   $1,053.55   $1,053.60   $1,053.50