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	$111.83	12.789%	$126.1319	$126.13	$126.15	$126.10
Purchase #2	$107.67	4.487%	$112.5012	$112.50	$112.50	$112.50
Purchase #3	$104.58	6.385%	$111.2574	$111.26	$111.25	$111.30
Purchase #4	$211.92	5.861%	$224.3406	$224.34	$224.35	$224.30
Purchase #5	$127.43	4.104%	$132.6597	$132.66	$132.65	$132.70
Purchase #6	$104.34	3.580%	$108.0754	$108.08	$108.10	$108.10
Purchase #7	$186.55	11.640%	$208.2644	$208.26	$208.25	$208.30
7 purchase totals =	$954.32		$1,023.2306	$1,023.23	$1,023.25	$1,023.30