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	$198.67	8.251%	$215.0623	$215.06	$215.05	$215.10
Purchase #2	$20.59	10.308%	$22.7124	$22.71	$22.70	$22.70
Purchase #3	$117.59	8.494%	$127.5781	$127.58	$127.60	$127.60
Purchase #4	$40.60	4.395%	$42.3844	$42.38	$42.40	$42.40
Purchase #5	$121.84	4.227%	$126.9902	$126.99	$127.00	$127.00
Purchase #6	$230.73	12.278%	$259.059	$259.06	$259.05	$259.10
Purchase #7	$208.65	7.576%	$224.4573	$224.46	$224.45	$224.50
7 purchase totals =	$938.67		$1,018.2437	$1,018.24	$1,018.25	$1,018.40