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	$51.86	3.262%	$53.5517	$53.55	$53.55	$53.60
Purchase #2	$43.51	5.143%	$45.7477	$45.75	$45.75	$45.70
Purchase #3	$9.63	6.530%	$10.2588	$10.26	$10.25	$10.30
Purchase #4	$34.50	8.143%	$37.3093	$37.31	$37.30	$37.30
Purchase #5	$222.85	9.681%	$244.4241	$244.42	$244.40	$244.40
Purchase #6	$105.61	5.324%	$111.2327	$111.23	$111.25	$111.20
Purchase #7	$250.76	3.551%	$259.6645	$259.66	$259.65	$259.70
7 purchase totals =	$718.72		$762.1888	$762.18	$762.15	$762.20