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	$196.27	9.494%	$214.9039	$214.90	$214.90	$214.90
Purchase #2	$217.59	5.867%	$230.356	$230.36	$230.35	$230.40
Purchase #3	$164.66	5.599%	$173.8793	$173.88	$173.90	$173.90
Purchase #4	$85.78	9.471%	$93.9042	$93.90	$93.90	$93.90
Purchase #5	$98.28	9.778%	$107.8898	$107.89	$107.90	$107.90
Purchase #6	$146.86	4.464%	$153.4158	$153.42	$153.40	$153.40
Purchase #7	$34.51	7.363%	$37.051	$37.05	$37.05	$37.10
7 purchase totals =	$943.95		$1,011.4000	$1,011.40	$1,011.40	$1,011.50