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	$178.25	4.147%	$185.642	$185.64	$185.65	$185.60
Purchase #2	$200.98	6.715%	$214.4758	$214.48	$214.50	$214.50
Purchase #3	$36.62	7.623%	$39.4115	$39.41	$39.40	$39.40
Purchase #4	$220.28	4.707%	$230.6486	$230.65	$230.65	$230.60
Purchase #5	$59.45	13.321%	$67.3693	$67.37	$67.35	$67.40
Purchase #6	$55.46	11.584%	$61.8845	$61.88	$61.90	$61.90
Purchase #7	$60.87	13.512%	$69.0948	$69.09	$69.10	$69.10
7 purchase totals =	$811.91		$868.5265	$868.52	$868.55	$868.50