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	$162.77	6.145%	$172.7722	$172.77	$172.75	$172.80
Purchase #2	$94.27	6.775%	$100.6568	$100.66	$100.65	$100.70
Purchase #3	$250.59	3.823%	$260.1701	$260.17	$260.15	$260.20
Purchase #4	$70.47	10.526%	$77.8877	$77.89	$77.90	$77.90
Purchase #5	$55.28	9.653%	$60.6162	$60.62	$60.60	$60.60
Purchase #6	$182.52	8.436%	$197.9174	$197.92	$197.90	$197.90
Purchase #7	$153.56	7.707%	$165.3949	$165.39	$165.40	$165.40
7 purchase totals =	$969.46		$1,035.4153	$1,035.42	$1,035.35	$1,035.50