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 $87.56   8.553%   $95.049   $95.05   $95.05   $95.00  
  Purchase #2 $159.26   8.140%   $172.2238   $172.22   $172.20   $172.20  
  Purchase #3 $146.99   8.496%   $159.4783   $159.48   $159.50   $159.50  
  Purchase #4 $145.76   10.461%   $161.008   $161.01   $161.00   $161.00  
  Purchase #5 $38.73   4.467%   $40.4601   $40.46   $40.45   $40.50  
  Purchase #6 $24.82   8.195%   $26.854   $26.85   $26.85   $26.90  
  Purchase #7 $237.65   11.337%   $264.5924   $264.59   $264.60   $264.60  
  7 purchase totals = $840.77       $919.6656   $919.66   $919.65   $919.70