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	$127.65	11.342%	$142.1281	$142.13	$142.15	$142.10
Purchase #2	$140.32	8.148%	$151.7533	$151.75	$151.75	$151.80
Purchase #3	$183.33	3.674%	$190.0655	$190.07	$190.05	$190.10
Purchase #4	$60.76	5.540%	$64.1261	$64.13	$64.15	$64.10
Purchase #5	$82.92	11.206%	$92.212	$92.21	$92.20	$92.20
Purchase #6	$58.29	10.798%	$64.5842	$64.58	$64.60	$64.60
Purchase #7	$9.44	8.804%	$10.2711	$10.27	$10.25	$10.30
7 purchase totals =	$662.71		$715.1403	$715.14	$715.15	$715.20