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	$146.39	5.627%	$154.6274	$154.63	$154.65	$154.60
Purchase #2	$107.29	5.388%	$113.0708	$113.07	$113.05	$113.10
Purchase #3	$113.58	7.672%	$122.2939	$122.29	$122.30	$122.30
Purchase #4	$183.48	3.792%	$190.4376	$190.44	$190.45	$190.40
Purchase #5	$167.90	10.456%	$185.4556	$185.46	$185.45	$185.50
Purchase #6	$138.92	10.527%	$153.5441	$153.54	$153.55	$153.50
Purchase #7	$174.89	12.379%	$196.5396	$196.54	$196.55	$196.50
7 purchase totals =	$1,032.45		$1,115.9690	$1,115.97	$1,116.00	$1,115.90