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	$208.47	3.182%	$215.1035	$215.10	$215.10	$215.10
Purchase #2	$151.45	7.161%	$162.2953	$162.30	$162.30	$162.30
Purchase #3	$118.74	7.558%	$127.7144	$127.71	$127.70	$127.70
Purchase #4	$11.89	13.425%	$13.4862	$13.49	$13.50	$13.50
Purchase #5	$131.32	11.861%	$146.8959	$146.90	$146.90	$146.90
Purchase #6	$228.38	4.186%	$237.94	$237.94	$237.95	$237.90
Purchase #7	$247.31	5.594%	$261.1445	$261.14	$261.15	$261.10
7 purchase totals =	$1,097.56		$1,164.5798	$1,164.58	$1,164.60	$1,164.50