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	$220.39	11.145%	$244.9525	$244.95	$244.95	$245.00
Purchase #2	$224.85	4.267%	$234.4443	$234.44	$234.45	$234.40
Purchase #3	$98.82	5.808%	$104.5595	$104.56	$104.55	$104.60
Purchase #4	$215.27	12.763%	$242.7449	$242.74	$242.75	$242.70
Purchase #5	$121.26	4.343%	$126.5263	$126.53	$126.55	$126.50
Purchase #6	$112.60	13.562%	$127.8708	$127.87	$127.85	$127.90
Purchase #7	$107.42	7.320%	$115.2831	$115.28	$115.30	$115.30
7 purchase totals =	$1,100.61		$1,196.3814	$1,196.37	$1,196.40	$1,196.40