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	$69.69	4.440%	$72.7842	$72.78	$72.80	$72.80
Purchase #2	$215.51	6.504%	$229.5268	$229.53	$229.55	$229.50
Purchase #3	$45.91	6.511%	$48.8992	$48.90	$48.90	$48.90
Purchase #4	$200.70	13.402%	$227.5978	$227.60	$227.60	$227.60
Purchase #5	$96.28	4.857%	$100.9563	$100.96	$100.95	$101.00
Purchase #6	$145.53	5.802%	$153.9737	$153.97	$153.95	$154.00
Purchase #7	$220.65	4.271%	$230.074	$230.07	$230.05	$230.10
7 purchase totals =	$994.27		$1,063.8120	$1,063.81	$1,063.80	$1,063.90