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	$197.56	10.754%	$218.8056	$218.81	$218.80	$218.80
Purchase #2	$205.80	3.136%	$212.2539	$212.25	$212.25	$212.30
Purchase #3	$45.89	12.211%	$51.4936	$51.49	$51.50	$51.50
Purchase #4	$215.72	12.154%	$241.9386	$241.94	$241.95	$241.90
Purchase #5	$185.33	3.428%	$191.6831	$191.68	$191.70	$191.70
Purchase #6	$49.89	4.545%	$52.1575	$52.16	$52.15	$52.20
Purchase #7	$116.70	9.390%	$127.6581	$127.66	$127.65	$127.70
7 purchase totals =	$1,016.89		$1,095.9904	$1,095.99	$1,096.00	$1,096.10