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	$85.68	11.158%	$95.2402	$95.24	$95.25	$95.20
Purchase #2	$31.80	12.503%	$35.776	$35.78	$35.80	$35.80
Purchase #3	$67.87	6.624%	$72.3657	$72.37	$72.35	$72.40
Purchase #4	$127.45	5.238%	$134.1258	$134.13	$134.15	$134.10
Purchase #5	$130.42	10.557%	$144.1884	$144.19	$144.20	$144.20
Purchase #6	$58.43	3.783%	$60.6404	$60.64	$60.65	$60.60
Purchase #7	$27.72	5.429%	$29.2249	$29.22	$29.20	$29.20
7 purchase totals =	$529.37		$571.5614	$571.57	$571.60	$571.50