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	$151.53	4.836%	$158.858	$158.86	$158.85	$158.90
Purchase #2	$13.76	9.253%	$15.0332	$15.03	$15.05	$15.00
Purchase #3	$130.29	3.291%	$134.5778	$134.58	$134.60	$134.60
Purchase #4	$134.51	5.145%	$141.4305	$141.43	$141.45	$141.40
Purchase #5	$245.29	6.623%	$261.5356	$261.54	$261.55	$261.50
Purchase #6	$248.68	8.301%	$269.3229	$269.32	$269.30	$269.30
Purchase #7	$52.65	3.631%	$54.5617	$54.56	$54.55	$54.60
7 purchase totals =	$976.71		$1,035.3197	$1,035.32	$1,035.35	$1,035.30