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	$102.74	5.430%	$108.3188	$108.32	$108.30	$108.30
Purchase #2	$11.40	3.822%	$11.8357	$11.84	$11.85	$11.80
Purchase #3	$153.99	7.343%	$165.2975	$165.30	$165.30	$165.30
Purchase #4	$148.33	11.496%	$165.382	$165.38	$165.40	$165.40
Purchase #5	$169.27	7.193%	$181.4456	$181.45	$181.45	$181.40
Purchase #6	$156.84	3.137%	$161.7601	$161.76	$161.75	$161.80
Purchase #7	$214.96	3.544%	$222.5782	$222.58	$222.60	$222.60
7 purchase totals =	$957.53		$1,016.6179	$1,016.63	$1,016.65	$1,016.60