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	$67.52	7.516%	$72.5948	$72.59	$72.60	$72.60
Purchase #2	$152.77	13.253%	$173.0166	$173.02	$173.00	$173.00
Purchase #3	$150.35	7.152%	$161.103	$161.10	$161.10	$161.10
Purchase #4	$146.87	12.387%	$165.0628	$165.06	$165.05	$165.10
Purchase #5	$188.45	10.704%	$208.6217	$208.62	$208.60	$208.60
Purchase #6	$59.72	10.849%	$66.199	$66.20	$66.20	$66.20
Purchase #7	$186.39	11.552%	$207.9218	$207.92	$207.90	$207.90
7 purchase totals =	$952.07		$1,054.5197	$1,054.51	$1,054.45	$1,054.50