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	$51.59	4.147%	$53.7294	$53.73	$53.75	$53.70
Purchase #2	$188.43	4.471%	$196.8547	$196.85	$196.85	$196.90
Purchase #3	$51.98	3.440%	$53.7681	$53.77	$53.75	$53.80
Purchase #4	$173.53	4.516%	$181.3666	$181.37	$181.35	$181.40
Purchase #5	$204.28	6.561%	$217.6828	$217.68	$217.70	$217.70
Purchase #6	$227.72	13.558%	$258.5943	$258.59	$258.60	$258.60
Purchase #7	$61.74	5.664%	$65.237	$65.24	$65.25	$65.20
7 purchase totals =	$959.27		$1,027.2329	$1,027.23	$1,027.25	$1,027.30