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	$118.64	6.217%	$126.0158	$126.02	$126.00	$126.00
Purchase #2	$153.60	3.121%	$158.3939	$158.39	$158.40	$158.40
Purchase #3	$165.51	4.256%	$172.5541	$172.55	$172.55	$172.60
Purchase #4	$188.62	4.384%	$196.8891	$196.89	$196.90	$196.90
Purchase #5	$244.42	7.379%	$262.4558	$262.46	$262.45	$262.50
Purchase #6	$138.91	12.170%	$155.8153	$155.82	$155.80	$155.80
Purchase #7	$158.66	8.376%	$171.9494	$171.95	$171.95	$171.90
7 purchase totals =	$1,168.36		$1,244.0734	$1,244.08	$1,244.05	$1,244.10