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	$83.44	11.340%	$92.9021	$92.90	$92.90	$92.90
Purchase #2	$114.67	8.451%	$124.3608	$124.36	$124.35	$124.40
Purchase #3	$106.65	4.487%	$111.4354	$111.44	$111.45	$111.40
Purchase #4	$157.71	10.274%	$173.9131	$173.91	$173.90	$173.90
Purchase #5	$208.54	5.391%	$219.7824	$219.78	$219.80	$219.80
Purchase #6	$82.95	11.699%	$92.6543	$92.65	$92.65	$92.70
Purchase #7	$194.51	3.623%	$201.5571	$201.56	$201.55	$201.60
7 purchase totals =	$948.47		$1,016.6052	$1,016.60	$1,016.60	$1,016.70