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	$187.45	11.243%	$208.525	$208.53	$208.55	$208.50
Purchase #2	$161.96	3.613%	$167.8116	$167.81	$167.80	$167.80
Purchase #3	$82.38	4.647%	$86.2082	$86.21	$86.20	$86.20
Purchase #4	$56.65	9.456%	$62.0068	$62.01	$62.00	$62.00
Purchase #5	$214.48	6.833%	$229.1354	$229.14	$229.15	$229.10
Purchase #6	$158.42	5.441%	$167.0396	$167.04	$167.05	$167.00
Purchase #7	$129.50	13.179%	$146.5668	$146.57	$146.55	$146.60
7 purchase totals =	$990.84		$1,067.2934	$1,067.31	$1,067.30	$1,067.20