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	$207.84	8.792%	$226.1133	$226.11	$226.10	$226.10
Purchase #2	$119.61	6.615%	$127.5222	$127.52	$127.50	$127.50
Purchase #3	$63.38	7.191%	$67.9377	$67.94	$67.95	$67.90
Purchase #4	$13.42	4.826%	$14.0676	$14.07	$14.05	$14.10
Purchase #5	$23.72	3.702%	$24.5981	$24.60	$24.60	$24.60
Purchase #6	$230.46	5.849%	$243.9396	$243.94	$243.95	$243.90
Purchase #7	$50.74	11.170%	$56.4077	$56.41	$56.40	$56.40
7 purchase totals =	$709.17		$760.5862	$760.59	$760.55	$760.50