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	$82.59	3.574%	$85.5418	$85.54	$85.55	$85.50
Purchase #2	$153.25	4.147%	$159.6053	$159.61	$159.60	$159.60
Purchase #3	$178.85	7.252%	$191.8202	$191.82	$191.80	$191.80
Purchase #4	$154.77	7.294%	$166.0589	$166.06	$166.05	$166.10
Purchase #5	$210.32	13.151%	$237.9792	$237.98	$238.00	$238.00
Purchase #6	$213.80	10.221%	$235.6525	$235.65	$235.65	$235.70
Purchase #7	$114.31	4.597%	$119.5648	$119.56	$119.55	$119.60
7 purchase totals =	$1,107.89		$1,196.2227	$1,196.22	$1,196.20	$1,196.30