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	$64.76	4.439%	$67.6347	$67.63	$67.65	$67.60
Purchase #2	$151.82	4.460%	$158.5912	$158.59	$158.60	$158.60
Purchase #3	$79.72	3.710%	$82.6776	$82.68	$82.70	$82.70
Purchase #4	$111.97	11.713%	$125.085	$125.09	$125.10	$125.10
Purchase #5	$34.43	7.707%	$37.0835	$37.08	$37.10	$37.10
Purchase #6	$15.46	13.736%	$17.5836	$17.58	$17.60	$17.60
Purchase #7	$232.65	9.395%	$254.5075	$254.51	$254.50	$254.50
7 purchase totals =	$690.81		$743.1631	$743.16	$743.25	$743.20