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	$107.99	4.606%	$112.964	$112.96	$112.95	$113.00
Purchase #2	$166.59	4.390%	$173.9033	$173.90	$173.90	$173.90
Purchase #3	$51.86	5.132%	$54.5215	$54.52	$54.50	$54.50
Purchase #4	$123.96	10.205%	$136.6101	$136.61	$136.60	$136.60
Purchase #5	$143.25	6.445%	$152.4825	$152.48	$152.50	$152.50
Purchase #6	$208.61	13.726%	$237.2438	$237.24	$237.25	$237.20
Purchase #7	$130.89	9.192%	$142.9214	$142.92	$142.90	$142.90
7 purchase totals =	$933.15		$1,010.6466	$1,010.63	$1,010.60	$1,010.60