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	$104.70	7.693%	$112.7546	$112.75	$112.75	$112.80
Purchase #2	$55.37	6.581%	$59.0139	$59.01	$59.00	$59.00
Purchase #3	$158.46	5.293%	$166.8473	$166.85	$166.85	$166.80
Purchase #4	$232.43	8.245%	$251.5939	$251.59	$251.60	$251.60
Purchase #5	$216.28	11.742%	$241.6756	$241.68	$241.70	$241.70
Purchase #6	$180.59	4.575%	$188.852	$188.85	$188.85	$188.90
Purchase #7	$151.89	10.153%	$167.3114	$167.31	$167.30	$167.30
7 purchase totals =	$1,099.72		$1,188.0487	$1,188.04	$1,188.05	$1,188.10