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 $62.64   8.470%   $67.9456   $67.95   $67.95   $67.90  
  Purchase #2 $101.34   3.217%   $104.6001   $104.60   $104.60   $104.60  
  Purchase #3 $132.98   3.152%   $137.1715   $137.17   $137.15   $137.20  
  Purchase #4 $229.35   4.541%   $239.7648   $239.76   $239.75   $239.80  
  Purchase #5 $234.39   13.246%   $265.4373   $265.44   $265.45   $265.40  
  Purchase #6 $23.61   7.553%   $25.3933   $25.39   $25.40   $25.40  
  Purchase #7 $168.32   8.409%   $182.474   $182.47   $182.45   $182.50  
  7 purchase totals = $952.63       $1,022.7866   $1,022.78   $1,022.75   $1,022.80