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	$161.64	9.162%	$176.4495	$176.45	$176.45	$176.40
Purchase #2	$157.67	12.617%	$177.5632	$177.56	$177.55	$177.60
Purchase #3	$141.59	11.610%	$158.0286	$158.03	$158.05	$158.00
Purchase #4	$80.57	11.453%	$89.7977	$89.80	$89.80	$89.80
Purchase #5	$115.69	10.370%	$127.6871	$127.69	$127.70	$127.70
Purchase #6	$206.67	3.584%	$214.0771	$214.08	$214.10	$214.10
Purchase #7	$137.31	10.440%	$151.6452	$151.65	$151.65	$151.60
7 purchase totals =	$1,001.14		$1,095.2484	$1,095.26	$1,095.30	$1,095.20