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	$245.39	4.282%	$255.8976	$255.90	$255.90	$255.90
Purchase #2	$14.34	4.144%	$14.9342	$14.93	$14.95	$14.90
Purchase #3	$112.90	5.833%	$119.4855	$119.49	$119.50	$119.50
Purchase #4	$230.42	11.677%	$257.3261	$257.33	$257.35	$257.30
Purchase #5	$89.87	11.267%	$99.9957	$100.00	$100.00	$100.00
Purchase #6	$230.58	10.430%	$254.6295	$254.63	$254.65	$254.60
Purchase #7	$182.84	6.125%	$194.039	$194.04	$194.05	$194.00
7 purchase totals =	$1,106.34		$1,196.3076	$1,196.32	$1,196.40	$1,196.20