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	$116.42	9.178%	$127.105	$127.11	$127.10	$127.10
Purchase #2	$20.58	8.229%	$22.2735	$22.27	$22.25	$22.30
Purchase #3	$222.75	12.419%	$250.4133	$250.41	$250.40	$250.40
Purchase #4	$49.28	7.848%	$53.1475	$53.15	$53.15	$53.10
Purchase #5	$137.49	3.217%	$141.9131	$141.91	$141.90	$141.90
Purchase #6	$238.38	8.345%	$258.2728	$258.27	$258.25	$258.30
Purchase #7	$206.86	3.742%	$214.6007	$214.60	$214.60	$214.60
7 purchase totals =	$991.76		$1,067.7259	$1,067.72	$1,067.65	$1,067.70