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	$194.29	10.371%	$214.4398	$214.44	$214.45	$214.40
Purchase #2	$98.52	12.654%	$110.9867	$110.99	$111.00	$111.00
Purchase #3	$42.63	6.296%	$45.314	$45.31	$45.30	$45.30
Purchase #4	$164.52	8.359%	$178.2722	$178.27	$178.25	$178.30
Purchase #5	$215.87	12.538%	$242.9358	$242.94	$242.95	$242.90
Purchase #6	$103.56	12.478%	$116.4822	$116.48	$116.50	$116.50
Purchase #7	$164.74	3.561%	$170.6064	$170.61	$170.60	$170.60
7 purchase totals =	$984.13		$1,079.0371	$1,079.04	$1,079.05	$1,079.00