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	$105.88	5.203%	$111.3889	$111.39	$111.40	$111.40
Purchase #2	$196.72	13.564%	$223.4031	$223.40	$223.40	$223.40
Purchase #3	$52.51	12.626%	$59.1399	$59.14	$59.15	$59.10
Purchase #4	$80.70	7.290%	$86.583	$86.58	$86.60	$86.60
Purchase #5	$241.45	8.193%	$261.232	$261.23	$261.25	$261.20
Purchase #6	$183.75	6.593%	$195.8646	$195.86	$195.85	$195.90
Purchase #7	$146.40	12.515%	$164.722	$164.72	$164.70	$164.70
7 purchase totals =	$1,007.41		$1,102.3335	$1,102.32	$1,102.35	$1,102.30