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	$149.38	12.253%	$167.6835	$167.68	$167.70	$167.70
Purchase #2	$23.81	3.752%	$24.7034	$24.70	$24.70	$24.70
Purchase #3	$185.64	5.771%	$196.3533	$196.35	$196.35	$196.40
Purchase #4	$51.80	5.227%	$54.5076	$54.51	$54.50	$54.50
Purchase #5	$202.42	9.574%	$221.7997	$221.80	$221.80	$221.80
Purchase #6	$158.89	5.636%	$167.845	$167.85	$167.85	$167.80
Purchase #7	$183.67	3.415%	$189.9423	$189.94	$189.95	$189.90
7 purchase totals =	$955.61		$1,022.8348	$1,022.83	$1,022.85	$1,022.80