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	$141.85	11.687%	$158.428	$158.43	$158.45	$158.40
Purchase #2	$60.56	11.750%	$67.6758	$67.68	$67.70	$67.70
Purchase #3	$80.78	9.579%	$88.5179	$88.52	$88.50	$88.50
Purchase #4	$229.67	11.792%	$256.7527	$256.75	$256.75	$256.80
Purchase #5	$109.31	12.556%	$123.035	$123.04	$123.05	$123.00
Purchase #6	$75.96	13.826%	$86.4622	$86.46	$86.45	$86.50
Purchase #7	$250.42	9.450%	$274.0847	$274.08	$274.10	$274.10
7 purchase totals =	$948.55		$1,054.9563	$1,054.96	$1,055.00	$1,055.00