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	$105.34	8.260%	$114.0411	$114.04	$114.05	$114.00
Purchase #2	$17.29	13.208%	$19.5737	$19.57	$19.55	$19.60
Purchase #3	$96.55	3.852%	$100.2691	$100.27	$100.25	$100.30
Purchase #4	$166.82	4.393%	$174.1484	$174.15	$174.15	$174.10
Purchase #5	$165.31	6.815%	$176.5759	$176.58	$176.60	$176.60
Purchase #6	$146.92	6.111%	$155.8983	$155.90	$155.90	$155.90
Purchase #7	$134.91	8.168%	$145.9294	$145.93	$145.95	$145.90
7 purchase totals =	$833.14		$886.4359	$886.44	$886.45	$886.40