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	$216.88	11.437%	$241.6846	$241.68	$241.70	$241.70
Purchase #2	$50.30	6.445%	$53.5418	$53.54	$53.55	$53.50
Purchase #3	$185.72	3.720%	$192.6288	$192.63	$192.65	$192.60
Purchase #4	$190.48	10.324%	$210.1452	$210.15	$210.15	$210.10
Purchase #5	$152.51	12.692%	$171.8666	$171.87	$171.85	$171.90
Purchase #6	$51.47	5.784%	$54.447	$54.45	$54.45	$54.40
Purchase #7	$74.42	9.217%	$81.2793	$81.28	$81.30	$81.30
7 purchase totals =	$921.78		$1,005.5933	$1,005.60	$1,005.65	$1,005.50