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	$168.54	10.327%	$185.9451	$185.95	$185.95	$185.90
Purchase #2	$29.86	9.137%	$32.5883	$32.59	$32.60	$32.60
Purchase #3	$219.59	13.749%	$249.7814	$249.78	$249.80	$249.80
Purchase #4	$13.86	4.412%	$14.4715	$14.47	$14.45	$14.50
Purchase #5	$168.88	8.815%	$183.7668	$183.77	$183.75	$183.80
Purchase #6	$199.67	10.419%	$220.4736	$220.47	$220.45	$220.50
Purchase #7	$164.99	11.767%	$184.4044	$184.40	$184.40	$184.40
7 purchase totals =	$965.39		$1,071.4311	$1,071.43	$1,071.40	$1,071.50