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	$165.49	4.339%	$172.6706	$172.67	$172.65	$172.70
Purchase #2	$213.71	9.279%	$233.5402	$233.54	$233.55	$233.50
Purchase #3	$16.46	4.125%	$17.139	$17.14	$17.15	$17.10
Purchase #4	$140.64	8.196%	$152.1669	$152.17	$152.15	$152.20
Purchase #5	$114.88	10.583%	$127.0378	$127.04	$127.05	$127.00
Purchase #6	$133.43	11.212%	$148.3902	$148.39	$148.40	$148.40
Purchase #7	$176.65	7.841%	$190.5011	$190.50	$190.50	$190.50
7 purchase totals =	$961.26		$1,041.4458	$1,041.45	$1,041.45	$1,041.40