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 $119.63   5.300%   $125.9704   $125.97   $125.95   $126.00  
  Purchase #2 $158.64   10.695%   $175.6065   $175.61   $175.60   $175.60  
  Purchase #3 $168.79   8.589%   $183.2874   $183.29   $183.30   $183.30  
  Purchase #4 $175.97   11.316%   $195.8828   $195.88   $195.90   $195.90  
  Purchase #5 $232.37   6.257%   $246.9094   $246.91   $246.90   $246.90  
  Purchase #6 $239.58   8.287%   $259.434   $259.43   $259.45   $259.40  
  Purchase #7 $23.85   12.551%   $26.8434   $26.84   $26.85   $26.80  
  7 purchase totals = $1,118.83       $1,213.9339   $1,213.93   $1,213.95   $1,213.90