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	$143.31	7.124%	$153.5194	$153.52	$153.50	$153.50
Purchase #2	$6.69	3.846%	$6.9473	$6.95	$6.95	$6.90
Purchase #3	$241.35	6.442%	$256.8978	$256.90	$256.90	$256.90
Purchase #4	$48.55	11.429%	$54.0988	$54.10	$54.10	$54.10
Purchase #5	$121.52	4.409%	$126.8778	$126.88	$126.90	$126.90
Purchase #6	$118.47	7.261%	$127.0721	$127.07	$127.05	$127.10
Purchase #7	$27.27	6.774%	$29.1173	$29.12	$29.10	$29.10
7 purchase totals =	$707.16		$754.5305	$754.54	$754.50	$754.50