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	$107.28	3.824%	$111.3824	$111.38	$111.40	$111.40
Purchase #2	$106.77	4.357%	$111.422	$111.42	$111.40	$111.40
Purchase #3	$127.73	7.540%	$137.3608	$137.36	$137.35	$137.40
Purchase #4	$78.33	7.211%	$83.9784	$83.98	$84.00	$84.00
Purchase #5	$207.27	13.866%	$236.0101	$236.01	$236.00	$236.00
Purchase #6	$167.40	3.526%	$173.3025	$173.30	$173.30	$173.30
Purchase #7	$205.83	4.602%	$215.3023	$215.30	$215.30	$215.30
7 purchase totals =	$1,000.61		$1,068.7585	$1,068.75	$1,068.75	$1,068.80