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	$118.61	6.377%	$126.1738	$126.17	$126.15	$126.20
Purchase #2	$208.59	8.336%	$225.9781	$225.98	$226.00	$226.00
Purchase #3	$9.50	10.716%	$10.518	$10.52	$10.50	$10.50
Purchase #4	$112.49	13.148%	$127.2802	$127.28	$127.30	$127.30
Purchase #5	$137.31	13.483%	$155.8235	$155.82	$155.80	$155.80
Purchase #6	$67.41	8.431%	$73.0933	$73.09	$73.10	$73.10
Purchase #7	$179.68	6.778%	$191.8587	$191.86	$191.85	$191.90
7 purchase totals =	$833.59		$910.7256	$910.72	$910.70	$910.80