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	$161.69	7.442%	$173.723	$173.72	$173.70	$173.70
Purchase #2	$187.31	11.489%	$208.83	$208.83	$208.85	$208.80
Purchase #3	$133.89	13.653%	$152.17	$152.17	$152.15	$152.20
Purchase #4	$205.92	3.278%	$212.6701	$212.67	$212.65	$212.70
Purchase #5	$59.96	8.504%	$65.059	$65.06	$65.05	$65.10
Purchase #6	$9.63	11.733%	$10.7599	$10.76	$10.75	$10.80
Purchase #7	$165.87	12.523%	$186.6419	$186.64	$186.65	$186.60
7 purchase totals =	$924.27		$1,009.8539	$1,009.85	$1,009.80	$1,009.90