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 $84.98   12.337%   $95.464   $95.46   $95.45   $95.50  
  Purchase #2 $226.30   9.178%   $247.0698   $247.07   $247.05   $247.10  
  Purchase #3 $59.91   3.568%   $62.0476   $62.05   $62.05   $62.00  
  Purchase #4 $177.76   4.506%   $185.7699   $185.77   $185.75   $185.80  
  Purchase #5 $225.66   4.482%   $235.7741   $235.77   $235.75   $235.80  
  Purchase #6 $215.93   8.275%   $233.7982   $233.80   $233.80   $233.80  
  Purchase #7 $101.75   3.302%   $105.1098   $105.11   $105.10   $105.10  
  7 purchase totals = $1,092.29       $1,165.0334   $1,165.03   $1,164.95   $1,165.10