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	$118.43	4.588%	$123.8636	$123.86	$123.85	$123.90
Purchase #2	$137.90	10.433%	$152.2871	$152.29	$152.30	$152.30
Purchase #3	$153.31	6.508%	$163.2874	$163.29	$163.30	$163.30
Purchase #4	$165.74	3.550%	$171.6238	$171.62	$171.60	$171.60
Purchase #5	$248.66	6.590%	$265.0467	$265.05	$265.05	$265.00
Purchase #6	$114.65	13.767%	$130.4339	$130.43	$130.45	$130.40
Purchase #7	$41.94	13.194%	$47.4736	$47.47	$47.45	$47.50
7 purchase totals =	$980.63		$1,054.0161	$1,054.01	$1,054.00	$1,054.00