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	$176.52	8.700%	$191.8772	$191.88	$191.90	$191.90
Purchase #2	$58.69	10.242%	$64.701	$64.70	$64.70	$64.70
Purchase #3	$183.42	3.575%	$189.9773	$189.98	$190.00	$190.00
Purchase #4	$171.41	4.672%	$179.4183	$179.42	$179.40	$179.40
Purchase #5	$172.38	6.329%	$183.2899	$183.29	$183.30	$183.30
Purchase #6	$167.64	3.546%	$173.5845	$173.58	$173.60	$173.60
Purchase #7	$126.95	13.868%	$144.5554	$144.56	$144.55	$144.60
7 purchase totals =	$1,057.01		$1,127.4036	$1,127.41	$1,127.45	$1,127.50