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	$154.66	5.183%	$162.676	$162.68	$162.70	$162.70
Purchase #2	$215.81	4.307%	$225.1049	$225.10	$225.10	$225.10
Purchase #3	$14.84	11.812%	$16.5929	$16.59	$16.60	$16.60
Purchase #4	$48.54	6.146%	$51.5233	$51.52	$51.50	$51.50
Purchase #5	$241.45	9.401%	$264.1487	$264.15	$264.15	$264.10
Purchase #6	$154.75	3.626%	$160.3612	$160.36	$160.35	$160.40
Purchase #7	$112.39	13.577%	$127.6492	$127.65	$127.65	$127.60
7 purchase totals =	$942.44		$1,008.0562	$1,008.05	$1,008.05	$1,008.00