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	$55.55	11.733%	$62.0677	$62.07	$62.05	$62.10
Purchase #2	$173.39	13.252%	$196.3676	$196.37	$196.35	$196.40
Purchase #3	$43.44	4.159%	$45.2467	$45.25	$45.25	$45.20
Purchase #4	$55.65	11.409%	$61.9991	$62.00	$62.00	$62.00
Purchase #5	$192.45	9.806%	$211.3216	$211.32	$211.30	$211.30
Purchase #6	$22.68	10.644%	$25.0941	$25.09	$25.10	$25.10
Purchase #7	$208.26	12.135%	$233.5324	$233.53	$233.55	$233.50
7 purchase totals =	$751.42		$835.6292	$835.63	$835.60	$835.60