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	$121.25	5.244%	$127.6084	$127.61	$127.60	$127.60
Purchase #2	$14.30	8.351%	$15.4942	$15.49	$15.50	$15.50
Purchase #3	$64.34	10.578%	$71.1459	$71.15	$71.15	$71.10
Purchase #4	$202.69	7.142%	$217.1661	$217.17	$217.15	$217.20
Purchase #5	$53.44	11.379%	$59.5209	$59.52	$59.50	$59.50
Purchase #6	$183.51	13.338%	$207.9866	$207.99	$208.00	$208.00
Purchase #7	$55.29	13.857%	$62.9515	$62.95	$62.95	$63.00
7 purchase totals =	$694.82		$761.8736	$761.88	$761.85	$761.90