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	$247.78	5.354%	$261.0461	$261.05	$261.05	$261.00
Purchase #2	$65.30	11.656%	$72.9114	$72.91	$72.90	$72.90
Purchase #3	$14.49	8.159%	$15.6722	$15.67	$15.65	$15.70
Purchase #4	$161.87	3.796%	$168.0146	$168.01	$168.00	$168.00
Purchase #5	$173.29	13.176%	$196.1227	$196.12	$196.10	$196.10
Purchase #6	$136.72	12.517%	$153.8332	$153.83	$153.85	$153.80
Purchase #7	$151.58	10.642%	$167.7111	$167.71	$167.70	$167.70
7 purchase totals =	$951.03		$1,035.3113	$1,035.30	$1,035.25	$1,035.20