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	$214.28	9.569%	$234.7845	$234.78	$234.80	$234.80
Purchase #2	$11.66	10.566%	$12.892	$12.89	$12.90	$12.90
Purchase #3	$181.30	12.862%	$204.6188	$204.62	$204.60	$204.60
Purchase #4	$49.40	9.267%	$53.9779	$53.98	$54.00	$54.00
Purchase #5	$122.32	10.179%	$134.771	$134.77	$134.75	$134.80
Purchase #6	$222.81	5.870%	$235.8889	$235.89	$235.90	$235.90
Purchase #7	$214.47	3.809%	$222.6392	$222.64	$222.65	$222.60
7 purchase totals =	$1,016.24		$1,099.5723	$1,099.57	$1,099.60	$1,099.60