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	$189.82	12.821%	$214.1568	$214.16	$214.15	$214.20
Purchase #2	$43.57	10.750%	$48.2538	$48.25	$48.25	$48.30
Purchase #3	$29.45	5.588%	$31.0957	$31.10	$31.10	$31.10
Purchase #4	$20.28	5.768%	$21.4498	$21.45	$21.45	$21.40
Purchase #5	$8.77	11.587%	$9.7862	$9.79	$9.80	$9.80
Purchase #6	$62.65	4.624%	$65.5469	$65.55	$65.55	$65.50
Purchase #7	$56.91	4.364%	$59.3936	$59.39	$59.40	$59.40
7 purchase totals =	$411.45		$449.6828	$449.69	$449.70	$449.70