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	$152.67	6.352%	$162.3676	$162.37	$162.35	$162.40
Purchase #2	$150.91	8.274%	$163.3963	$163.40	$163.40	$163.40
Purchase #3	$41.81	3.359%	$43.2144	$43.21	$43.20	$43.20
Purchase #4	$160.89	5.149%	$169.1742	$169.17	$169.15	$169.20
Purchase #5	$177.86	10.486%	$196.5104	$196.51	$196.50	$196.50
Purchase #6	$196.78	8.480%	$213.4669	$213.47	$213.45	$213.50
Purchase #7	$208.86	5.243%	$219.8105	$219.81	$219.80	$219.80
7 purchase totals =	$1,089.78		$1,167.9403	$1,167.94	$1,167.85	$1,168.00