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	$126.58	4.401%	$132.1508	$132.15	$132.15	$132.20
Purchase #2	$144.60	4.277%	$150.7845	$150.78	$150.80	$150.80
Purchase #3	$191.68	9.811%	$210.4857	$210.49	$210.50	$210.50
Purchase #4	$227.60	12.531%	$256.1206	$256.12	$256.10	$256.10
Purchase #5	$230.25	13.757%	$261.9255	$261.93	$261.95	$261.90
Purchase #6	$22.56	11.363%	$25.1235	$25.12	$25.10	$25.10
Purchase #7	$115.44	10.815%	$127.9248	$127.92	$127.90	$127.90
7 purchase totals =	$1,058.71		$1,164.5154	$1,164.51	$1,164.50	$1,164.50