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	$127.80	4.526%	$133.5842	$133.58	$133.60	$133.60
Purchase #2	$197.27	3.430%	$204.0364	$204.04	$204.05	$204.00
Purchase #3	$214.76	7.528%	$230.9271	$230.93	$230.95	$230.90
Purchase #4	$105.36	5.606%	$111.2665	$111.27	$111.25	$111.30
Purchase #5	$38.94	4.226%	$40.5856	$40.59	$40.60	$40.60
Purchase #6	$118.56	10.226%	$130.6839	$130.68	$130.70	$130.70
Purchase #7	$156.56	11.489%	$174.5472	$174.55	$174.55	$174.50
7 purchase totals =	$959.25		$1,025.6309	$1,025.64	$1,025.70	$1,025.60