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	$161.76	8.287%	$175.1651	$175.17	$175.15	$175.20
Purchase #2	$12.75	6.806%	$13.6178	$13.62	$13.60	$13.60
Purchase #3	$164.34	10.306%	$181.2769	$181.28	$181.30	$181.30
Purchase #4	$226.56	5.220%	$238.3864	$238.39	$238.40	$238.40
Purchase #5	$30.51	6.296%	$32.4309	$32.43	$32.45	$32.40
Purchase #6	$227.84	12.146%	$255.5134	$255.51	$255.50	$255.50
Purchase #7	$96.27	7.720%	$103.702	$103.70	$103.70	$103.70
7 purchase totals =	$920.03		$1,000.0925	$1,000.10	$1,000.10	$1,000.10