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	$195.84	11.707%	$218.767	$218.77	$218.75	$218.80
Purchase #2	$103.79	10.327%	$114.5084	$114.51	$114.50	$114.50
Purchase #3	$198.56	4.825%	$208.1405	$208.14	$208.15	$208.10
Purchase #4	$17.26	11.670%	$19.2742	$19.27	$19.25	$19.30
Purchase #5	$214.90	11.757%	$240.1658	$240.17	$240.15	$240.20
Purchase #6	$97.55	11.233%	$108.5078	$108.51	$108.50	$108.50
Purchase #7	$127.81	7.616%	$137.544	$137.54	$137.55	$137.50
7 purchase totals =	$955.71		$1,046.9077	$1,046.91	$1,046.85	$1,046.90