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	$116.45	9.504%	$127.5174	$127.52	$127.50	$127.50
Purchase #2	$185.90	10.412%	$205.2559	$205.26	$205.25	$205.30
Purchase #3	$160.89	6.646%	$171.5827	$171.58	$171.60	$171.60
Purchase #4	$120.71	13.609%	$137.1374	$137.14	$137.15	$137.10
Purchase #5	$53.52	13.635%	$60.8175	$60.82	$60.80	$60.80
Purchase #6	$239.61	4.583%	$250.5913	$250.59	$250.60	$250.60
Purchase #7	$177.71	11.338%	$197.8588	$197.86	$197.85	$197.90
7 purchase totals =	$1,054.79		$1,150.7610	$1,150.77	$1,150.75	$1,150.80