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	$51.94	4.560%	$54.3085	$54.31	$54.30	$54.30
Purchase #2	$187.55	4.509%	$196.0066	$196.01	$196.00	$196.00
Purchase #3	$204.58	4.416%	$213.6143	$213.61	$213.60	$213.60
Purchase #4	$185.84	3.506%	$192.3556	$192.36	$192.35	$192.40
Purchase #5	$179.40	9.287%	$196.0609	$196.06	$196.05	$196.10
Purchase #6	$210.81	8.848%	$229.4625	$229.46	$229.45	$229.50
Purchase #7	$201.90	9.267%	$220.6101	$220.61	$220.60	$220.60
7 purchase totals =	$1,222.02		$1,302.4185	$1,302.42	$1,302.35	$1,302.50