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	$204.98	4.863%	$214.9482	$214.95	$214.95	$214.90
Purchase #2	$117.59	8.128%	$127.1477	$127.15	$127.15	$127.10
Purchase #3	$143.60	5.808%	$151.9403	$151.94	$151.95	$151.90
Purchase #4	$30.89	6.280%	$32.8299	$32.83	$32.85	$32.80
Purchase #5	$110.37	5.310%	$116.2306	$116.23	$116.25	$116.20
Purchase #6	$149.39	10.542%	$165.1387	$165.14	$165.15	$165.10
Purchase #7	$17.27	13.190%	$19.5479	$19.55	$19.55	$19.50
7 purchase totals =	$774.09		$827.7833	$827.79	$827.85	$827.50