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 $112.26   5.713%   $118.6734   $118.67   $118.65   $118.70  
  Purchase #2 $246.71   11.661%   $275.4789   $275.48   $275.50   $275.50  
  Purchase #3 $199.76   4.343%   $208.4356   $208.44   $208.45   $208.40  
  Purchase #4 $68.87   7.652%   $74.1399   $74.14   $74.15   $74.10  
  Purchase #5 $120.70   3.472%   $124.8907   $124.89   $124.90   $124.90  
  Purchase #6 $186.81   8.181%   $202.0929   $202.09   $202.10   $202.10  
  Purchase #7 $84.25   9.184%   $91.9875   $91.99   $92.00   $92.00  
  7 purchase totals = $1,019.36       $1,095.6989   $1,095.70   $1,095.75   $1,095.70