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	$105.89	5.755%	$111.984	$111.98	$112.00	$112.00
Purchase #2	$34.35	9.150%	$37.493	$37.49	$37.50	$37.50
Purchase #3	$176.44	9.183%	$192.6425	$192.64	$192.65	$192.60
Purchase #4	$99.52	3.745%	$103.247	$103.25	$103.25	$103.20
Purchase #5	$61.71	12.394%	$69.3583	$69.36	$69.35	$69.40
Purchase #6	$20.60	12.266%	$23.1268	$23.13	$23.15	$23.10
Purchase #7	$219.39	13.281%	$248.5272	$248.53	$248.55	$248.50
7 purchase totals =	$717.90		$786.3788	$786.38	$786.45	$786.30