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	$146.94	7.548%	$158.031	$158.03	$158.05	$158.00
Purchase #2	$248.43	7.417%	$266.8561	$266.86	$266.85	$266.90
Purchase #3	$235.92	12.702%	$265.8866	$265.89	$265.90	$265.90
Purchase #4	$58.92	3.174%	$60.7901	$60.79	$60.80	$60.80
Purchase #5	$96.40	4.504%	$100.7419	$100.74	$100.75	$100.70
Purchase #6	$103.89	7.507%	$111.689	$111.69	$111.70	$111.70
Purchase #7	$135.81	9.541%	$148.7676	$148.77	$148.75	$148.80
7 purchase totals =	$1,026.31		$1,112.7623	$1,112.77	$1,112.80	$1,112.80