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 $59.38   4.506%   $62.0557   $62.06   $62.05   $62.10  
  Purchase #2 $247.44   4.776%   $259.2577   $259.26   $259.25   $259.30  
  Purchase #3 $163.78   4.814%   $171.6644   $171.66   $171.65   $171.70  
  Purchase #4 $221.64   13.743%   $252.1   $252.10   $252.10   $252.10  
  Purchase #5 $14.68   8.484%   $15.9255   $15.93   $15.95   $15.90  
  Purchase #6 $112.55   10.343%   $124.191   $124.19   $124.20   $124.20  
  Purchase #7 $61.82   9.646%   $67.7832   $67.78   $67.80   $67.80  
  7 purchase totals = $881.29       $952.9775   $952.98   $953.00   $953.10