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	$56.30	4.308%	$58.7254	$58.73	$58.75	$58.70
Purchase #2	$43.49	3.378%	$44.9591	$44.96	$44.95	$45.00
Purchase #3	$56.92	4.602%	$59.5395	$59.54	$59.55	$59.50
Purchase #4	$126.83	12.838%	$143.1124	$143.11	$143.10	$143.10
Purchase #5	$231.25	4.335%	$241.2747	$241.27	$241.25	$241.30
Purchase #6	$244.37	13.745%	$277.9587	$277.96	$277.95	$278.00
Purchase #7	$227.65	7.120%	$243.8587	$243.86	$243.85	$243.90
7 purchase totals =	$986.81		$1,069.4285	$1,069.43	$1,069.40	$1,069.50