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	$207.25	11.389%	$230.8537	$230.85	$230.85	$230.90
Purchase #2	$177.69	4.516%	$185.7145	$185.71	$185.70	$185.70
Purchase #3	$110.78	9.217%	$120.9906	$120.99	$121.00	$121.00
Purchase #4	$127.65	7.624%	$137.382	$137.38	$137.40	$137.40
Purchase #5	$83.98	6.344%	$89.3077	$89.31	$89.30	$89.30
Purchase #6	$136.52	7.379%	$146.5938	$146.59	$146.60	$146.60
Purchase #7	$155.52	4.332%	$162.2571	$162.26	$162.25	$162.30
7 purchase totals =	$999.39		$1,073.0994	$1,073.09	$1,073.10	$1,073.20