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	$113.85	8.324%	$123.3269	$123.33	$123.35	$123.30
Purchase #2	$14.27	4.694%	$14.9398	$14.94	$14.95	$14.90
Purchase #3	$56.37	4.815%	$59.0842	$59.08	$59.10	$59.10
Purchase #4	$247.54	5.788%	$261.8676	$261.87	$261.85	$261.90
Purchase #5	$192.47	4.123%	$200.4055	$200.41	$200.40	$200.40
Purchase #6	$129.42	12.416%	$145.4888	$145.49	$145.50	$145.50
Purchase #7	$48.39	4.640%	$50.6353	$50.64	$50.65	$50.60
7 purchase totals =	$802.31		$855.7481	$855.76	$855.80	$855.70