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	$97.48	13.819%	$110.9508	$110.95	$110.95	$111.00
Purchase #2	$151.87	4.128%	$158.1392	$158.14	$158.15	$158.10
Purchase #3	$157.55	8.741%	$171.3214	$171.32	$171.30	$171.30
Purchase #4	$172.70	13.737%	$196.4238	$196.42	$196.40	$196.40
Purchase #5	$66.94	6.565%	$71.3346	$71.33	$71.35	$71.30
Purchase #6	$148.82	7.604%	$160.1363	$160.14	$160.15	$160.10
Purchase #7	$148.62	9.766%	$163.1342	$163.13	$163.15	$163.10
7 purchase totals =	$943.98		$1,031.4403	$1,031.43	$1,031.45	$1,031.30