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	$157.88	3.157%	$162.8643	$162.86	$162.85	$162.90
Purchase #2	$146.81	5.461%	$154.8273	$154.83	$154.85	$154.80
Purchase #3	$239.42	3.612%	$248.0679	$248.07	$248.05	$248.10
Purchase #4	$50.71	6.635%	$54.0746	$54.07	$54.05	$54.10
Purchase #5	$153.49	7.499%	$165.0002	$165.00	$165.00	$165.00
Purchase #6	$233.38	9.714%	$256.0505	$256.05	$256.05	$256.10
Purchase #7	$93.92	10.128%	$103.4322	$103.43	$103.45	$103.40
7 purchase totals =	$1,075.61		$1,144.3170	$1,144.31	$1,144.30	$1,144.40