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	$199.49	9.156%	$217.7553	$217.76	$217.75	$217.80
Purchase #2	$17.37	9.803%	$19.0728	$19.07	$19.05	$19.10
Purchase #3	$114.74	3.502%	$118.7582	$118.76	$118.75	$118.80
Purchase #4	$181.39	8.198%	$196.2604	$196.26	$196.25	$196.30
Purchase #5	$41.59	9.283%	$45.4508	$45.45	$45.45	$45.50
Purchase #6	$145.82	3.589%	$151.0535	$151.05	$151.05	$151.10
Purchase #7	$47.32	13.497%	$53.7068	$53.71	$53.70	$53.70
7 purchase totals =	$747.72		$802.0578	$802.06	$802.00	$802.30