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	$174.94	12.855%	$197.4285	$197.43	$197.45	$197.40
Purchase #2	$126.73	13.667%	$144.0502	$144.05	$144.05	$144.10
Purchase #3	$64.71	11.757%	$72.318	$72.32	$72.30	$72.30
Purchase #4	$193.84	3.378%	$200.3879	$200.39	$200.40	$200.40
Purchase #5	$22.50	7.638%	$24.2186	$24.22	$24.20	$24.20
Purchase #6	$113.90	4.127%	$118.6007	$118.60	$118.60	$118.60
Purchase #7	$105.92	4.363%	$110.5413	$110.54	$110.55	$110.50
7 purchase totals =	$802.54		$867.5452	$867.55	$867.55	$867.50