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	$106.75	4.860%	$111.9381	$111.94	$111.95	$111.90
Purchase #2	$225.68	13.332%	$255.7677	$255.77	$255.75	$255.80
Purchase #3	$175.83	6.566%	$187.375	$187.38	$187.40	$187.40
Purchase #4	$16.81	3.158%	$17.3409	$17.34	$17.35	$17.30
Purchase #5	$242.38	11.856%	$271.1166	$271.12	$271.10	$271.10
Purchase #6	$128.32	10.445%	$141.723	$141.72	$141.70	$141.70
Purchase #7	$148.82	10.430%	$164.3419	$164.34	$164.35	$164.30
7 purchase totals =	$1,044.59		$1,149.6032	$1,149.61	$1,149.60	$1,149.50