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	$205.43	3.135%	$211.8702	$211.87	$211.85	$211.90
Purchase #2	$43.83	5.349%	$46.1745	$46.17	$46.15	$46.20
Purchase #3	$250.69	7.492%	$269.4717	$269.47	$269.45	$269.50
Purchase #4	$178.39	4.422%	$186.2784	$186.28	$186.30	$186.30
Purchase #5	$242.80	5.162%	$255.3333	$255.33	$255.35	$255.30
Purchase #6	$22.82	11.582%	$25.463	$25.46	$25.45	$25.50
Purchase #7	$9.98	4.484%	$10.4275	$10.43	$10.45	$10.40
7 purchase totals =	$953.94		$1,005.0186	$1,005.01	$1,005.00	$1,005.10