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	$127.71	11.642%	$142.578	$142.58	$142.60	$142.60
Purchase #2	$73.31	11.790%	$81.9532	$81.95	$81.95	$82.00
Purchase #3	$138.85	8.795%	$151.0619	$151.06	$151.05	$151.10
Purchase #4	$248.32	13.352%	$281.4757	$281.48	$281.50	$281.50
Purchase #5	$60.52	11.699%	$67.6002	$67.60	$67.60	$67.60
Purchase #6	$210.91	11.479%	$235.1204	$235.12	$235.10	$235.10
Purchase #7	$105.35	12.345%	$118.3555	$118.36	$118.35	$118.40
7 purchase totals =	$964.97		$1,078.1449	$1,078.15	$1,078.15	$1,078.30