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	$116.68	9.232%	$127.4519	$127.45	$127.45	$127.50
Purchase #2	$146.52	4.502%	$153.1163	$153.12	$153.10	$153.10
Purchase #3	$145.60	11.381%	$162.1707	$162.17	$162.15	$162.20
Purchase #4	$158.31	8.685%	$172.0592	$172.06	$172.05	$172.10
Purchase #5	$112.80	9.597%	$123.6254	$123.63	$123.65	$123.60
Purchase #6	$183.62	3.663%	$190.346	$190.35	$190.35	$190.30
Purchase #7	$130.36	8.278%	$141.1512	$141.15	$141.15	$141.20
7 purchase totals =	$993.89		$1,069.9207	$1,069.93	$1,069.90	$1,070.00