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	$222.51	7.161%	$238.4439	$238.44	$238.45	$238.40
Purchase #2	$43.85	6.227%	$46.5805	$46.58	$46.60	$46.60
Purchase #3	$171.35	9.848%	$188.2245	$188.22	$188.20	$188.20
Purchase #4	$127.98	12.297%	$143.7177	$143.72	$143.70	$143.70
Purchase #5	$104.83	13.545%	$119.0292	$119.03	$119.05	$119.00
Purchase #6	$156.58	7.637%	$168.538	$168.54	$168.55	$168.50
Purchase #7	$111.92	6.652%	$119.3649	$119.36	$119.35	$119.40
7 purchase totals =	$939.02		$1,023.8987	$1,023.89	$1,023.90	$1,023.80