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	$200.59	6.612%	$213.853	$213.85	$213.85	$213.90
Purchase #2	$68.55	12.618%	$77.1996	$77.20	$77.20	$77.20
Purchase #3	$171.86	4.643%	$179.8395	$179.84	$179.85	$179.80
Purchase #4	$80.65	10.433%	$89.0642	$89.06	$89.05	$89.10
Purchase #5	$112.38	3.253%	$116.0357	$116.04	$116.05	$116.00
Purchase #6	$214.32	6.757%	$228.8016	$228.80	$228.80	$228.80
Purchase #7	$151.80	10.123%	$167.1667	$167.17	$167.15	$167.20
7 purchase totals =	$1,000.15		$1,071.9603	$1,071.96	$1,071.95	$1,072.00