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	$214.60	4.796%	$224.8922	$224.89	$224.90	$224.90
Purchase #2	$20.82	8.630%	$22.6168	$22.62	$22.60	$22.60
Purchase #3	$50.43	6.806%	$53.8623	$53.86	$53.85	$53.90
Purchase #4	$82.65	9.526%	$90.5232	$90.52	$90.50	$90.50
Purchase #5	$72.85	8.532%	$79.0656	$79.07	$79.05	$79.10
Purchase #6	$219.87	6.817%	$234.8585	$234.86	$234.85	$234.90
Purchase #7	$53.73	5.508%	$56.6894	$56.69	$56.70	$56.70
7 purchase totals =	$714.95		$762.5080	$762.51	$762.45	$762.60