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	$228.86	3.324%	$236.4673	$236.47	$236.45	$236.50
Purchase #2	$45.47	7.241%	$48.7625	$48.76	$48.75	$48.80
Purchase #3	$146.27	5.470%	$154.271	$154.27	$154.25	$154.30
Purchase #4	$56.73	7.140%	$60.7805	$60.78	$60.80	$60.80
Purchase #5	$118.68	7.761%	$127.8908	$127.89	$127.90	$127.90
Purchase #6	$91.87	7.328%	$98.6022	$98.60	$98.60	$98.60
Purchase #7	$247.81	8.374%	$268.5616	$268.56	$268.55	$268.60
7 purchase totals =	$935.69		$995.3359	$995.33	$995.30	$995.50