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	$111.87	4.431%	$116.827	$116.83	$116.85	$116.80
Purchase #2	$55.25	7.292%	$59.2788	$59.28	$59.30	$59.30
Purchase #3	$134.74	5.442%	$142.0726	$142.07	$142.05	$142.10
Purchase #4	$88.42	13.758%	$100.5848	$100.58	$100.60	$100.60
Purchase #5	$236.31	7.555%	$254.1632	$254.16	$254.15	$254.20
Purchase #6	$242.73	9.781%	$266.4714	$266.47	$266.45	$266.50
Purchase #7	$127.49	8.805%	$138.7155	$138.72	$138.70	$138.70
7 purchase totals =	$996.81		$1,078.1133	$1,078.11	$1,078.10	$1,078.20