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	$173.55	13.161%	$196.3909	$196.39	$196.40	$196.40
Purchase #2	$18.76	6.168%	$19.9171	$19.92	$19.90	$19.90
Purchase #3	$18.93	5.310%	$19.9352	$19.94	$19.95	$19.90
Purchase #4	$19.37	8.687%	$21.0527	$21.05	$21.05	$21.10
Purchase #5	$249.96	4.247%	$260.5758	$260.58	$260.60	$260.60
Purchase #6	$12.53	6.303%	$13.3198	$13.32	$13.30	$13.30
Purchase #7	$143.69	10.150%	$158.2745	$158.27	$158.25	$158.30
7 purchase totals =	$636.79		$689.4660	$689.47	$689.45	$689.50