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	$69.72	9.116%	$76.0757	$76.08	$76.10	$76.10
Purchase #2	$192.70	11.175%	$214.2342	$214.23	$214.25	$214.20
Purchase #3	$217.79	4.463%	$227.51	$227.51	$227.50	$227.50
Purchase #4	$57.59	3.318%	$59.5008	$59.50	$59.50	$59.50
Purchase #5	$135.68	11.298%	$151.0091	$151.01	$151.00	$151.00
Purchase #6	$101.82	6.312%	$108.2469	$108.25	$108.25	$108.20
Purchase #7	$215.57	10.764%	$238.774	$238.77	$238.75	$238.80
7 purchase totals =	$990.87		$1,075.3507	$1,075.35	$1,075.35	$1,075.30