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	$124.88	13.675%	$141.9573	$141.96	$141.95	$142.00
Purchase #2	$126.33	4.297%	$131.7584	$131.76	$131.75	$131.80
Purchase #3	$75.68	4.194%	$78.854	$78.85	$78.85	$78.90
Purchase #4	$139.52	4.492%	$145.7872	$145.79	$145.80	$145.80
Purchase #5	$171.48	9.555%	$187.8649	$187.86	$187.85	$187.90
Purchase #6	$184.70	3.678%	$191.4933	$191.49	$191.50	$191.50
Purchase #7	$158.30	7.774%	$170.6062	$170.61	$170.60	$170.60
7 purchase totals =	$980.89		$1,048.3213	$1,048.32	$1,048.30	$1,048.50