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	$104.96	8.623%	$114.0107	$114.01	$114.00	$114.00
Purchase #2	$83.29	6.516%	$88.7172	$88.72	$88.70	$88.70
Purchase #3	$111.98	3.736%	$116.1636	$116.16	$116.15	$116.20
Purchase #4	$12.68	5.637%	$13.3948	$13.39	$13.40	$13.40
Purchase #5	$48.86	11.780%	$54.6157	$54.62	$54.60	$54.60
Purchase #6	$105.61	5.209%	$111.1112	$111.11	$111.10	$111.10
Purchase #7	$183.84	9.162%	$200.6834	$200.68	$200.70	$200.70
7 purchase totals =	$651.22		$698.6966	$698.69	$698.65	$698.70