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	$219.99	9.563%	$241.0276	$241.03	$241.05	$241.00
Purchase #2	$156.60	9.379%	$171.2875	$171.29	$171.30	$171.30
Purchase #3	$179.39	9.336%	$196.1379	$196.14	$196.15	$196.10
Purchase #4	$90.84	10.633%	$100.499	$100.50	$100.50	$100.50
Purchase #5	$149.45	4.576%	$156.2888	$156.29	$156.30	$156.30
Purchase #6	$204.67	3.565%	$211.9665	$211.97	$211.95	$212.00
Purchase #7	$142.83	5.627%	$150.867	$150.87	$150.85	$150.90
7 purchase totals =	$1,143.77		$1,228.0743	$1,228.09	$1,228.10	$1,228.10