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	$113.34	12.215%	$127.1845	$127.18	$127.20	$127.20
Purchase #2	$18.46	6.643%	$19.6863	$19.69	$19.70	$19.70
Purchase #3	$81.51	5.222%	$85.7665	$85.77	$85.75	$85.80
Purchase #4	$100.30	5.309%	$105.6249	$105.62	$105.60	$105.60
Purchase #5	$141.71	8.729%	$154.0799	$154.08	$154.10	$154.10
Purchase #6	$242.31	12.292%	$272.0947	$272.09	$272.10	$272.10
Purchase #7	$30.84	5.120%	$32.419	$32.42	$32.40	$32.40
7 purchase totals =	$728.47		$796.8558	$796.85	$796.85	$796.90