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	$213.41	5.866%	$225.9286	$225.93	$225.95	$225.90
Purchase #2	$164.76	12.664%	$185.6252	$185.63	$185.65	$185.60
Purchase #3	$57.34	6.495%	$61.0642	$61.06	$61.05	$61.10
Purchase #4	$43.76	10.866%	$48.515	$48.52	$48.50	$48.50
Purchase #5	$158.43	5.424%	$167.0232	$167.02	$167.00	$167.00
Purchase #6	$128.35	4.813%	$134.5275	$134.53	$134.55	$134.50
Purchase #7	$39.47	5.823%	$41.7683	$41.77	$41.75	$41.80
7 purchase totals =	$805.52		$864.4520	$864.46	$864.45	$864.40