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	$177.37	4.712%	$185.7277	$185.73	$185.75	$185.70
Purchase #2	$76.30	12.292%	$85.6788	$85.68	$85.70	$85.70
Purchase #3	$102.69	8.574%	$111.4946	$111.49	$111.50	$111.50
Purchase #4	$235.50	11.591%	$262.7968	$262.80	$262.80	$262.80
Purchase #5	$56.74	13.322%	$64.2989	$64.30	$64.30	$64.30
Purchase #6	$122.78	3.727%	$127.356	$127.36	$127.35	$127.40
Purchase #7	$193.37	12.347%	$217.2454	$217.25	$217.25	$217.20
7 purchase totals =	$964.75		$1,054.5982	$1,054.61	$1,054.65	$1,054.60