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	$130.48	10.531%	$144.2208	$144.22	$144.20	$144.20
Purchase #2	$11.41	11.177%	$12.6853	$12.69	$12.70	$12.70
Purchase #3	$80.81	11.140%	$89.8122	$89.81	$89.80	$89.80
Purchase #4	$211.78	9.421%	$231.7318	$231.73	$231.75	$231.70
Purchase #5	$235.65	7.386%	$253.0551	$253.06	$253.05	$253.10
Purchase #6	$108.60	7.813%	$117.0849	$117.08	$117.10	$117.10
Purchase #7	$164.54	5.393%	$173.4136	$173.41	$173.40	$173.40
7 purchase totals =	$943.27		$1,022.0037	$1,022.00	$1,022.00	$1,022.00