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	$169.46	13.720%	$192.7099	$192.71	$192.70	$192.70
Purchase #2	$200.53	12.232%	$225.0588	$225.06	$225.05	$225.10
Purchase #3	$101.40	7.655%	$109.1622	$109.16	$109.15	$109.20
Purchase #4	$99.81	5.485%	$105.2846	$105.28	$105.30	$105.30
Purchase #5	$114.78	7.467%	$123.3506	$123.35	$123.35	$123.40
Purchase #6	$59.95	7.744%	$64.5925	$64.59	$64.60	$64.60
Purchase #7	$240.38	13.764%	$273.4659	$273.47	$273.45	$273.50
7 purchase totals =	$986.31		$1,093.6245	$1,093.62	$1,093.60	$1,093.80