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	$190.75	9.164%	$208.2303	$208.23	$208.25	$208.20
Purchase #2	$5.31	9.540%	$5.8166	$5.82	$5.80	$5.80
Purchase #3	$101.38	9.654%	$111.1672	$111.17	$111.15	$111.20
Purchase #4	$9.56	7.684%	$10.2946	$10.29	$10.30	$10.30
Purchase #5	$228.34	5.632%	$241.2001	$241.20	$241.20	$241.20
Purchase #6	$162.45	7.485%	$174.6094	$174.61	$174.60	$174.60
Purchase #7	$230.25	12.847%	$259.8302	$259.83	$259.85	$259.80
7 purchase totals =	$928.04		$1,011.1484	$1,011.15	$1,011.15	$1,011.10