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	$130.41	8.679%	$141.7283	$141.73	$141.75	$141.70
Purchase #2	$151.58	4.394%	$158.2404	$158.24	$158.25	$158.20
Purchase #3	$156.26	10.665%	$172.9251	$172.93	$172.95	$172.90
Purchase #4	$54.45	10.167%	$59.9859	$59.99	$60.00	$60.00
Purchase #5	$172.30	13.824%	$196.1188	$196.12	$196.10	$196.10
Purchase #6	$104.42	7.389%	$112.1356	$112.14	$112.15	$112.10
Purchase #7	$24.73	5.741%	$26.1497	$26.15	$26.15	$26.10
7 purchase totals =	$794.15		$867.2838	$867.30	$867.35	$867.10