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	$116.34	9.251%	$127.1026	$127.10	$127.10	$127.10
Purchase #2	$186.85	11.526%	$208.3863	$208.39	$208.40	$208.40
Purchase #3	$111.81	11.719%	$124.913	$124.91	$124.90	$124.90
Purchase #4	$161.47	8.131%	$174.5991	$174.60	$174.60	$174.60
Purchase #5	$156.49	13.832%	$178.1357	$178.14	$178.15	$178.10
Purchase #6	$101.38	10.210%	$111.7309	$111.73	$111.75	$111.70
Purchase #7	$125.70	6.325%	$133.6505	$133.65	$133.65	$133.70
7 purchase totals =	$960.04		$1,058.5181	$1,058.52	$1,058.55	$1,058.50