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	$218.35	10.778%	$241.8838	$241.88	$241.90	$241.90
Purchase #2	$100.67	4.329%	$105.028	$105.03	$105.05	$105.00
Purchase #3	$195.52	10.676%	$216.3937	$216.39	$216.40	$216.40
Purchase #4	$55.87	11.453%	$62.2688	$62.27	$62.25	$62.30
Purchase #5	$241.87	12.524%	$272.1618	$272.16	$272.15	$272.20
Purchase #6	$231.97	10.609%	$256.5797	$256.58	$256.60	$256.60
Purchase #7	$9.27	8.495%	$10.0575	$10.06	$10.05	$10.10
7 purchase totals =	$1,053.52		$1,164.3733	$1,164.37	$1,164.40	$1,164.50