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	$87.31	9.350%	$95.4735	$95.47	$95.45	$95.50
Purchase #2	$247.38	13.797%	$281.511	$281.51	$281.50	$281.50
Purchase #3	$141.76	8.209%	$153.3971	$153.40	$153.40	$153.40
Purchase #4	$238.89	6.807%	$255.1512	$255.15	$255.15	$255.20
Purchase #5	$235.96	5.272%	$248.3998	$248.40	$248.40	$248.40
Purchase #6	$72.99	7.784%	$78.6715	$78.67	$78.65	$78.70
Purchase #7	$99.94	7.296%	$107.2316	$107.23	$107.25	$107.20
7 purchase totals =	$1,124.23		$1,219.8357	$1,219.83	$1,219.80	$1,219.90