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	$178.31	11.153%	$198.1969	$198.20	$198.20	$198.20
Purchase #2	$222.56	13.608%	$252.846	$252.85	$252.85	$252.80
Purchase #3	$46.86	4.350%	$48.8984	$48.90	$48.90	$48.90
Purchase #4	$200.89	5.325%	$211.5874	$211.59	$211.60	$211.60
Purchase #5	$220.64	7.689%	$237.605	$237.61	$237.60	$237.60
Purchase #6	$10.49	11.756%	$11.7232	$11.72	$11.70	$11.70
Purchase #7	$245.39	4.196%	$255.6866	$255.69	$255.70	$255.70
7 purchase totals =	$1,125.14		$1,216.5435	$1,216.56	$1,216.55	$1,216.50