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	$115.64	10.264%	$127.5093	$127.51	$127.50	$127.50
Purchase #2	$11.50	8.108%	$12.4324	$12.43	$12.45	$12.40
Purchase #3	$61.39	4.130%	$63.9254	$63.93	$63.95	$63.90
Purchase #4	$224.93	11.860%	$251.6067	$251.61	$251.60	$251.60
Purchase #5	$191.63	7.243%	$205.5098	$205.51	$205.50	$205.50
Purchase #6	$146.58	9.247%	$160.1343	$160.13	$160.15	$160.10
Purchase #7	$215.78	3.601%	$223.5502	$223.55	$223.55	$223.60
7 purchase totals =	$967.45		$1,044.6681	$1,044.67	$1,044.70	$1,044.60