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	$218.94	10.283%	$241.4536	$241.45	$241.45	$241.50
Purchase #2	$50.96	8.861%	$55.4756	$55.48	$55.50	$55.50
Purchase #3	$131.29	3.696%	$136.1425	$136.14	$136.15	$136.10
Purchase #4	$247.85	4.251%	$258.3861	$258.39	$258.40	$258.40
Purchase #5	$153.36	13.202%	$173.6066	$173.61	$173.60	$173.60
Purchase #6	$203.29	12.865%	$229.4433	$229.44	$229.45	$229.40
Purchase #7	$37.65	12.709%	$42.4349	$42.43	$42.45	$42.40
7 purchase totals =	$1,043.34		$1,136.9426	$1,136.94	$1,137.00	$1,136.90