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	$165.48	11.799%	$185.005	$185.01	$185.00	$185.00
Purchase #2	$37.27	3.822%	$38.6945	$38.69	$38.70	$38.70
Purchase #3	$105.55	7.656%	$113.6309	$113.63	$113.65	$113.60
Purchase #4	$54.27	13.446%	$61.5671	$61.57	$61.55	$61.60
Purchase #5	$214.45	13.817%	$244.0806	$244.08	$244.10	$244.10
Purchase #6	$148.81	11.291%	$165.6121	$165.61	$165.60	$165.60
Purchase #7	$124.34	7.509%	$133.6767	$133.68	$133.70	$133.70
7 purchase totals =	$850.17		$942.2669	$942.27	$942.30	$942.30