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	$86.86	10.141%	$95.6685	$95.67	$95.65	$95.70
Purchase #2	$113.67	8.521%	$123.3558	$123.36	$123.35	$123.40
Purchase #3	$214.39	3.357%	$221.5871	$221.59	$221.60	$221.60
Purchase #4	$185.54	5.802%	$196.305	$196.31	$196.30	$196.30
Purchase #5	$244.45	4.163%	$254.6265	$254.63	$254.65	$254.60
Purchase #6	$99.57	6.559%	$106.1008	$106.10	$106.10	$106.10
Purchase #7	$59.51	3.236%	$61.4357	$61.44	$61.45	$61.40
7 purchase totals =	$1,003.99		$1,059.0794	$1,059.10	$1,059.10	$1,059.10