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	$202.50	5.634%	$213.9089	$213.91	$213.90	$213.90
Purchase #2	$11.29	10.780%	$12.5071	$12.51	$12.50	$12.50
Purchase #3	$156.69	11.255%	$174.3255	$174.33	$174.35	$174.30
Purchase #4	$188.57	13.702%	$214.4079	$214.41	$214.40	$214.40
Purchase #5	$116.92	9.204%	$127.6813	$127.68	$127.70	$127.70
Purchase #6	$238.27	7.688%	$256.5882	$256.59	$256.60	$256.60
Purchase #7	$176.69	4.862%	$185.2807	$185.28	$185.30	$185.30
7 purchase totals =	$1,090.93		$1,184.6996	$1,184.71	$1,184.75	$1,184.70