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	$173.52	13.255%	$196.5201	$196.52	$196.50	$196.50
Purchase #2	$57.25	9.373%	$62.616	$62.62	$62.60	$62.60
Purchase #3	$53.81	13.763%	$61.2159	$61.22	$61.20	$61.20
Purchase #4	$175.62	5.523%	$185.3195	$185.32	$185.30	$185.30
Purchase #5	$165.75	6.448%	$176.4376	$176.44	$176.45	$176.40
Purchase #6	$141.31	12.500%	$158.9738	$158.97	$158.95	$159.00
Purchase #7	$158.81	8.109%	$171.6879	$171.69	$171.70	$171.70
7 purchase totals =	$926.07		$1,012.7708	$1,012.78	$1,012.70	$1,012.70