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	$184.28	11.488%	$205.4501	$205.45	$205.45	$205.50
Purchase #2	$29.34	11.627%	$32.7514	$32.75	$32.75	$32.80
Purchase #3	$55.70	10.731%	$61.6772	$61.68	$61.70	$61.70
Purchase #4	$185.87	3.346%	$192.0892	$192.09	$192.10	$192.10
Purchase #5	$141.38	13.358%	$160.2655	$160.27	$160.25	$160.30
Purchase #6	$231.50	5.856%	$245.0566	$245.06	$245.05	$245.10
Purchase #7	$67.72	6.274%	$71.9688	$71.97	$71.95	$72.00
7 purchase totals =	$895.79		$969.2588	$969.27	$969.25	$969.50