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	$95.25	5.445%	$100.4364	$100.44	$100.45	$100.40
Purchase #2	$115.97	5.205%	$122.0062	$122.01	$122.00	$122.00
Purchase #3	$149.97	10.301%	$165.4184	$165.42	$165.40	$165.40
Purchase #4	$221.58	10.490%	$244.8237	$244.82	$244.80	$244.80
Purchase #5	$59.52	4.617%	$62.268	$62.27	$62.25	$62.30
Purchase #6	$230.51	11.191%	$256.3064	$256.31	$256.30	$256.30
Purchase #7	$92.63	10.378%	$102.2431	$102.24	$102.25	$102.20
7 purchase totals =	$965.43		$1,053.5022	$1,053.51	$1,053.45	$1,053.40