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	$223.88	4.328%	$233.5695	$233.57	$233.55	$233.60
Purchase #2	$238.55	8.564%	$258.9794	$258.98	$259.00	$259.00
Purchase #3	$54.40	4.375%	$56.78	$56.78	$56.80	$56.80
Purchase #4	$130.39	4.390%	$136.1141	$136.11	$136.10	$136.10
Purchase #5	$127.78	11.435%	$142.3916	$142.39	$142.40	$142.40
Purchase #6	$144.76	11.616%	$161.5753	$161.58	$161.60	$161.60
Purchase #7	$213.92	9.121%	$233.4316	$233.43	$233.45	$233.40
7 purchase totals =	$1,133.68		$1,222.8415	$1,222.84	$1,222.90	$1,222.90