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	$175.69	4.750%	$184.0353	$184.04	$184.05	$184.00
Purchase #2	$31.60	3.674%	$32.761	$32.76	$32.75	$32.80
Purchase #3	$161.65	13.518%	$183.5018	$183.50	$183.50	$183.50
Purchase #4	$118.65	3.105%	$122.3341	$122.33	$122.35	$122.30
Purchase #5	$10.34	11.540%	$11.5332	$11.53	$11.55	$11.50
Purchase #6	$105.75	5.457%	$111.5208	$111.52	$111.50	$111.50
Purchase #7	$158.88	7.636%	$171.0121	$171.01	$171.00	$171.00
7 purchase totals =	$762.56		$816.6983	$816.69	$816.70	$816.60