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	$167.26	13.691%	$190.1596	$190.16	$190.15	$190.20
Purchase #2	$48.88	11.737%	$54.617	$54.62	$54.60	$54.60
Purchase #3	$138.51	13.437%	$157.1216	$157.12	$157.10	$157.10
Purchase #4	$122.45	4.327%	$127.7484	$127.75	$127.75	$127.70
Purchase #5	$142.66	7.333%	$153.1213	$153.12	$153.10	$153.10
Purchase #6	$122.88	11.639%	$137.182	$137.18	$137.20	$137.20
Purchase #7	$39.71	6.860%	$42.4341	$42.43	$42.45	$42.40
7 purchase totals =	$782.35		$862.3840	$862.38	$862.35	$862.30