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	$216.68	13.333%	$245.5699	$245.57	$245.55	$245.60
Purchase #2	$144.54	13.780%	$164.4576	$164.46	$164.45	$164.50
Purchase #3	$26.39	4.595%	$27.6026	$27.60	$27.60	$27.60
Purchase #4	$105.88	5.841%	$112.0645	$112.06	$112.05	$112.10
Purchase #5	$242.60	6.519%	$258.4151	$258.42	$258.40	$258.40
Purchase #6	$150.65	3.353%	$155.7013	$155.70	$155.70	$155.70
Purchase #7	$110.99	11.663%	$123.9348	$123.93	$123.95	$123.90
7 purchase totals =	$997.73		$1,087.7458	$1,087.74	$1,087.70	$1,087.80