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	$213.25	3.848%	$221.4559	$221.46	$221.45	$221.50
Purchase #2	$108.69	13.615%	$123.4881	$123.49	$123.50	$123.50
Purchase #3	$84.33	4.716%	$88.307	$88.31	$88.30	$88.30
Purchase #4	$183.81	3.411%	$190.0798	$190.08	$190.10	$190.10
Purchase #5	$41.86	3.366%	$43.269	$43.27	$43.25	$43.30
Purchase #6	$173.81	10.748%	$192.4911	$192.49	$192.50	$192.50
Purchase #7	$190.85	3.525%	$197.5775	$197.58	$197.60	$197.60
7 purchase totals =	$996.60		$1,056.6684	$1,056.68	$1,056.70	$1,056.80