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	$152.38	5.763%	$161.1617	$161.16	$161.15	$161.20
Purchase #2	$178.31	11.131%	$198.1577	$198.16	$198.15	$198.20
Purchase #3	$115.81	10.416%	$127.8728	$127.87	$127.85	$127.90
Purchase #4	$119.36	12.671%	$134.4841	$134.48	$134.50	$134.50
Purchase #5	$103.26	7.599%	$111.1067	$111.11	$111.10	$111.10
Purchase #6	$22.49	13.384%	$25.5001	$25.50	$25.50	$25.50
Purchase #7	$232.60	10.697%	$257.4812	$257.48	$257.50	$257.50
7 purchase totals =	$924.21		$1,015.7643	$1,015.76	$1,015.75	$1,015.90