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	$214.37	8.699%	$233.018	$233.02	$233.00	$233.00
Purchase #2	$18.53	4.476%	$19.3594	$19.36	$19.35	$19.40
Purchase #3	$42.86	3.271%	$44.262	$44.26	$44.25	$44.30
Purchase #4	$101.46	11.839%	$113.4718	$113.47	$113.45	$113.50
Purchase #5	$100.32	5.571%	$105.9088	$105.91	$105.90	$105.90
Purchase #6	$70.51	4.821%	$73.9093	$73.91	$73.90	$73.90
Purchase #7	$172.42	12.587%	$194.1225	$194.12	$194.10	$194.10
7 purchase totals =	$720.47		$784.0518	$784.05	$783.95	$784.10