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	$157.34	11.176%	$174.9243	$174.92	$174.90	$174.90
Purchase #2	$165.58	11.733%	$185.0075	$185.01	$185.00	$185.00
Purchase #3	$43.40	4.452%	$45.3322	$45.33	$45.35	$45.30
Purchase #4	$176.92	3.675%	$183.4218	$183.42	$183.40	$183.40
Purchase #5	$112.71	13.114%	$127.4908	$127.49	$127.50	$127.50
Purchase #6	$167.28	12.388%	$188.0026	$188.00	$188.00	$188.00
Purchase #7	$198.69	5.422%	$209.463	$209.46	$209.45	$209.50
7 purchase totals =	$1,021.92		$1,113.6422	$1,113.63	$1,113.60	$1,113.60