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	$194.66	11.822%	$217.6727	$217.67	$217.65	$217.70
Purchase #2	$193.99	12.507%	$218.2523	$218.25	$218.25	$218.30
Purchase #3	$179.69	9.352%	$196.4946	$196.49	$196.50	$196.50
Purchase #4	$59.75	8.130%	$64.6077	$64.61	$64.60	$64.60
Purchase #5	$179.93	10.415%	$198.6697	$198.67	$198.65	$198.70
Purchase #6	$14.91	3.539%	$15.4377	$15.44	$15.45	$15.40
Purchase #7	$238.35	7.293%	$255.7329	$255.73	$255.75	$255.70
7 purchase totals =	$1,061.28		$1,166.8676	$1,166.86	$1,166.85	$1,166.90