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	$156.49	4.102%	$162.9092	$162.91	$162.90	$162.90
Purchase #2	$248.35	5.521%	$262.0614	$262.06	$262.05	$262.10
Purchase #3	$185.38	3.721%	$192.278	$192.28	$192.30	$192.30
Purchase #4	$52.69	5.575%	$55.6275	$55.63	$55.65	$55.60
Purchase #5	$172.38	10.188%	$189.9421	$189.94	$189.95	$189.90
Purchase #6	$48.68	7.275%	$52.2215	$52.22	$52.20	$52.20
Purchase #7	$241.72	9.828%	$265.4762	$265.48	$265.50	$265.50
7 purchase totals =	$1,105.69		$1,180.5159	$1,180.52	$1,180.55	$1,180.50