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	$176.41	13.418%	$200.0807	$200.08	$200.10	$200.10
Purchase #2	$134.33	13.592%	$152.5881	$152.59	$152.60	$152.60
Purchase #3	$136.61	4.818%	$143.1919	$143.19	$143.20	$143.20
Purchase #4	$187.76	6.778%	$200.4864	$200.49	$200.50	$200.50
Purchase #5	$89.64	10.856%	$99.3713	$99.37	$99.35	$99.40
Purchase #6	$138.71	12.440%	$155.9655	$155.97	$155.95	$156.00
Purchase #7	$94.64	5.400%	$99.7506	$99.75	$99.75	$99.80
7 purchase totals =	$958.10		$1,051.4345	$1,051.44	$1,051.45	$1,051.60