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	$148.95	3.858%	$154.6965	$154.70	$154.70	$154.70
Purchase #2	$149.67	4.620%	$156.5848	$156.58	$156.60	$156.60
Purchase #3	$205.42	7.518%	$220.8635	$220.86	$220.85	$220.90
Purchase #4	$205.42	5.357%	$216.4243	$216.42	$216.40	$216.40
Purchase #5	$54.58	13.258%	$61.8162	$61.82	$61.80	$61.80
Purchase #6	$220.82	9.738%	$242.3235	$242.32	$242.30	$242.30
Purchase #7	$38.38	11.246%	$42.6962	$42.70	$42.70	$42.70
7 purchase totals =	$1,023.24		$1,095.4050	$1,095.40	$1,095.35	$1,095.40