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	$146.36	11.197%	$162.7479	$162.75	$162.75	$162.70
Purchase #2	$132.45	10.497%	$146.3533	$146.35	$146.35	$146.40
Purchase #3	$165.96	6.545%	$176.8221	$176.82	$176.80	$176.80
Purchase #4	$185.49	5.852%	$196.3449	$196.34	$196.35	$196.30
Purchase #5	$153.51	9.160%	$167.5715	$167.57	$167.55	$167.60
Purchase #6	$89.99	4.249%	$93.8137	$93.81	$93.80	$93.80
Purchase #7	$116.51	9.712%	$127.8255	$127.83	$127.85	$127.80
7 purchase totals =	$990.27		$1,071.4789	$1,071.47	$1,071.45	$1,071.40