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	$183.26	8.318%	$198.5036	$198.50	$198.50	$198.50
Purchase #2	$167.44	9.476%	$183.3066	$183.31	$183.30	$183.30
Purchase #3	$158.47	8.783%	$172.3884	$172.39	$172.40	$172.40
Purchase #4	$176.37	12.173%	$197.8395	$197.84	$197.85	$197.80
Purchase #5	$54.33	10.105%	$59.82	$59.82	$59.80	$59.80
Purchase #6	$188.95	8.253%	$204.544	$204.54	$204.55	$204.50
Purchase #7	$62.40	13.146%	$70.6031	$70.60	$70.60	$70.60
7 purchase totals =	$991.22		$1,087.0052	$1,087.00	$1,087.00	$1,086.90