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	$40.40	12.525%	$45.4601	$45.46	$45.45	$45.50
Purchase #2	$10.47	9.181%	$11.4313	$11.43	$11.45	$11.40
Purchase #3	$122.87	3.857%	$127.6091	$127.61	$127.60	$127.60
Purchase #4	$144.91	4.523%	$151.4643	$151.46	$151.45	$151.50
Purchase #5	$189.78	12.622%	$213.734	$213.73	$213.75	$213.70
Purchase #6	$209.40	11.465%	$233.4077	$233.41	$233.40	$233.40
Purchase #7	$142.77	7.421%	$153.365	$153.37	$153.35	$153.40
7 purchase totals =	$860.60		$936.4715	$936.47	$936.45	$936.50