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	$176.55	13.571%	$200.5096	$200.51	$200.50	$200.50
Purchase #2	$75.49	3.277%	$77.9638	$77.96	$77.95	$78.00
Purchase #3	$55.43	3.552%	$57.3989	$57.40	$57.40	$57.40
Purchase #4	$127.60	3.175%	$131.6513	$131.65	$131.65	$131.70
Purchase #5	$146.42	6.563%	$156.0295	$156.03	$156.05	$156.00
Purchase #6	$140.39	3.635%	$145.4932	$145.49	$145.50	$145.50
Purchase #7	$68.45	13.133%	$77.4395	$77.44	$77.45	$77.40
7 purchase totals =	$790.33		$846.4858	$846.48	$846.50	$846.50