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	$41.41	10.298%	$45.6744	$45.67	$45.65	$45.70
Purchase #2	$204.70	4.565%	$214.0446	$214.04	$214.05	$214.00
Purchase #3	$247.71	12.282%	$278.1337	$278.13	$278.15	$278.10
Purchase #4	$51.69	4.724%	$54.1318	$54.13	$54.15	$54.10
Purchase #5	$53.45	6.339%	$56.8382	$56.84	$56.85	$56.80
Purchase #6	$230.39	10.210%	$253.9128	$253.91	$253.90	$253.90
Purchase #7	$155.51	8.865%	$169.296	$169.30	$169.30	$169.30
7 purchase totals =	$984.86		$1,072.0315	$1,072.02	$1,072.05	$1,071.90