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	$171.40	6.182%	$181.9959	$182.00	$182.00	$182.00
Purchase #2	$21.29	7.589%	$22.9057	$22.91	$22.90	$22.90
Purchase #3	$73.26	6.592%	$78.0893	$78.09	$78.10	$78.10
Purchase #4	$17.61	4.769%	$18.4498	$18.45	$18.45	$18.40
Purchase #5	$248.89	9.426%	$272.3504	$272.35	$272.35	$272.40
Purchase #6	$113.85	8.520%	$123.55	$123.55	$123.55	$123.60
Purchase #7	$154.34	7.302%	$165.6099	$165.61	$165.60	$165.60
7 purchase totals =	$800.64		$862.9510	$862.96	$862.95	$863.00