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	$173.85	3.313%	$179.6097	$179.61	$179.60	$179.60
Purchase #2	$24.40	3.237%	$25.1898	$25.19	$25.20	$25.20
Purchase #3	$43.61	11.460%	$48.6077	$48.61	$48.60	$48.60
Purchase #4	$112.63	9.619%	$123.4639	$123.46	$123.45	$123.50
Purchase #5	$157.93	10.177%	$174.0025	$174.00	$174.00	$174.00
Purchase #6	$233.58	8.260%	$252.8737	$252.87	$252.85	$252.90
Purchase #7	$117.83	4.794%	$123.4788	$123.48	$123.50	$123.50
7 purchase totals =	$863.83		$927.2261	$927.22	$927.20	$927.30