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	$14.38	3.451%	$14.8763	$14.88	$14.90	$14.90
Purchase #2	$24.32	13.532%	$27.611	$27.61	$27.60	$27.60
Purchase #3	$65.37	13.733%	$74.3473	$74.35	$74.35	$74.30
Purchase #4	$170.48	11.677%	$190.3869	$190.39	$190.40	$190.40
Purchase #5	$238.79	9.781%	$262.146	$262.15	$262.15	$262.10
Purchase #6	$240.54	7.782%	$259.2588	$259.26	$259.25	$259.30
Purchase #7	$222.72	6.653%	$237.5376	$237.54	$237.55	$237.50
7 purchase totals =	$976.60		$1,066.1639	$1,066.18	$1,066.20	$1,066.10