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	$176.60	4.871%	$185.2022	$185.20	$185.20	$185.20
Purchase #2	$32.35	3.439%	$33.4625	$33.46	$33.45	$33.50
Purchase #3	$101.82	9.668%	$111.664	$111.66	$111.65	$111.70
Purchase #4	$42.50	7.667%	$45.7585	$45.76	$45.75	$45.80
Purchase #5	$65.95	6.249%	$70.0712	$70.07	$70.05	$70.10
Purchase #6	$211.61	11.332%	$235.5896	$235.59	$235.60	$235.60
Purchase #7	$172.77	6.323%	$183.6942	$183.69	$183.70	$183.70
7 purchase totals =	$803.60		$865.4422	$865.43	$865.40	$865.60