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	$182.35	10.153%	$200.864	$200.86	$200.85	$200.90
Purchase #2	$189.89	11.631%	$211.9761	$211.98	$212.00	$212.00
Purchase #3	$153.86	8.674%	$167.2058	$167.21	$167.20	$167.20
Purchase #4	$128.94	7.111%	$138.1089	$138.11	$138.10	$138.10
Purchase #5	$118.43	7.589%	$127.4177	$127.42	$127.40	$127.40
Purchase #6	$74.52	4.656%	$77.9897	$77.99	$78.00	$78.00
Purchase #7	$81.92	4.255%	$85.4057	$85.41	$85.40	$85.40
7 purchase totals =	$929.91		$1,008.9679	$1,008.98	$1,008.95	$1,009.00