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	$233.61	12.200%	$262.1104	$262.11	$262.10	$262.10
Purchase #2	$83.92	10.191%	$92.4723	$92.47	$92.45	$92.50
Purchase #3	$53.43	11.856%	$59.7647	$59.76	$59.75	$59.80
Purchase #4	$215.36	12.114%	$241.4487	$241.45	$241.45	$241.40
Purchase #5	$20.74	5.426%	$21.8654	$21.87	$21.85	$21.90
Purchase #6	$130.64	4.723%	$136.8101	$136.81	$136.80	$136.80
Purchase #7	$215.52	9.126%	$235.1884	$235.19	$235.20	$235.20
7 purchase totals =	$953.22		$1,049.6600	$1,049.66	$1,049.60	$1,049.70