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	$90.75	3.514%	$93.939	$93.94	$93.95	$93.90
Purchase #2	$184.49	6.748%	$196.9394	$196.94	$196.95	$196.90
Purchase #3	$13.78	3.672%	$14.286	$14.29	$14.30	$14.30
Purchase #4	$229.56	9.151%	$250.567	$250.57	$250.55	$250.60
Purchase #5	$147.84	12.522%	$166.3525	$166.35	$166.35	$166.40
Purchase #6	$237.73	7.455%	$255.4528	$255.45	$255.45	$255.50
Purchase #7	$231.93	3.506%	$240.0615	$240.06	$240.05	$240.10
7 purchase totals =	$1,136.08		$1,217.5982	$1,217.60	$1,217.60	$1,217.70