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	$185.54	13.801%	$211.1464	$211.15	$211.15	$211.10
Purchase #2	$112.38	13.370%	$127.4052	$127.41	$127.40	$127.40
Purchase #3	$119.68	5.818%	$126.643	$126.64	$126.65	$126.60
Purchase #4	$29.63	6.244%	$31.4801	$31.48	$31.50	$31.50
Purchase #5	$120.96	13.583%	$137.39	$137.39	$137.40	$137.40
Purchase #6	$197.48	13.569%	$224.2761	$224.28	$224.30	$224.30
Purchase #7	$191.51	11.834%	$214.1733	$214.17	$214.15	$214.20
7 purchase totals =	$957.18		$1,072.5141	$1,072.52	$1,072.55	$1,072.50