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	$144.64	7.520%	$155.5169	$155.52	$155.50	$155.50
Purchase #2	$168.27	8.116%	$181.9268	$181.93	$181.95	$181.90
Purchase #3	$185.38	5.444%	$195.4721	$195.47	$195.45	$195.50
Purchase #4	$54.27	9.314%	$59.3247	$59.32	$59.30	$59.30
Purchase #5	$83.30	9.341%	$91.0811	$91.08	$91.10	$91.10
Purchase #6	$233.37	6.205%	$247.8506	$247.85	$247.85	$247.90
Purchase #7	$108.59	8.866%	$118.2176	$118.22	$118.20	$118.20
7 purchase totals =	$977.82		$1,049.3898	$1,049.39	$1,049.35	$1,049.40