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	$112.98	11.760%	$126.2664	$126.27	$126.25	$126.30
Purchase #2	$63.50	7.567%	$68.305	$68.31	$68.30	$68.30
Purchase #3	$219.87	3.176%	$226.8531	$226.85	$226.85	$226.90
Purchase #4	$157.56	5.125%	$165.635	$165.64	$165.65	$165.60
Purchase #5	$225.42	13.677%	$256.2507	$256.25	$256.25	$256.30
Purchase #6	$53.30	12.196%	$59.8005	$59.80	$59.80	$59.80
Purchase #7	$135.53	4.275%	$141.3239	$141.32	$141.30	$141.30
7 purchase totals =	$968.16		$1,044.4346	$1,044.44	$1,044.40	$1,044.50