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	$43.65	8.478%	$47.3506	$47.35	$47.35	$47.40
Purchase #2	$128.87	12.418%	$144.8731	$144.87	$144.85	$144.90
Purchase #3	$196.90	9.323%	$215.257	$215.26	$215.25	$215.30
Purchase #4	$115.30	10.731%	$127.6728	$127.67	$127.65	$127.70
Purchase #5	$214.27	7.611%	$230.5781	$230.58	$230.60	$230.60
Purchase #6	$162.74	11.672%	$181.735	$181.74	$181.75	$181.70
Purchase #7	$105.49	7.584%	$113.4904	$113.49	$113.50	$113.50
7 purchase totals =	$967.22		$1,060.9570	$1,060.96	$1,060.95	$1,061.10