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	$183.30	7.208%	$196.5123	$196.51	$196.50	$196.50
Purchase #2	$5.64	7.490%	$6.0624	$6.06	$6.05	$6.10
Purchase #3	$77.50	13.828%	$88.2167	$88.22	$88.20	$88.20
Purchase #4	$46.43	8.857%	$50.5423	$50.54	$50.55	$50.50
Purchase #5	$127.51	5.305%	$134.2744	$134.27	$134.25	$134.30
Purchase #6	$150.42	5.783%	$159.1188	$159.12	$159.10	$159.10
Purchase #7	$96.47	12.559%	$108.5857	$108.59	$108.60	$108.60
7 purchase totals =	$687.27		$743.3126	$743.31	$743.25	$743.30