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	$211.88	5.455%	$223.4381	$223.44	$223.45	$223.40
Purchase #2	$231.30	13.227%	$261.8941	$261.89	$261.90	$261.90
Purchase #3	$97.42	6.348%	$103.6042	$103.60	$103.60	$103.60
Purchase #4	$63.39	3.353%	$65.5155	$65.52	$65.50	$65.50
Purchase #5	$158.41	9.447%	$173.375	$173.38	$173.40	$173.40
Purchase #6	$72.66	13.217%	$82.2635	$82.26	$82.25	$82.30
Purchase #7	$163.65	6.359%	$174.0565	$174.06	$174.05	$174.10
7 purchase totals =	$998.71		$1,084.1469	$1,084.15	$1,084.15	$1,084.20