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	$148.58	9.407%	$162.5569	$162.56	$162.55	$162.60
Purchase #2	$82.70	3.844%	$85.879	$85.88	$85.90	$85.90
Purchase #3	$155.98	13.194%	$176.56	$176.56	$176.55	$176.60
Purchase #4	$106.64	11.665%	$119.0796	$119.08	$119.10	$119.10
Purchase #5	$34.88	12.218%	$39.1416	$39.14	$39.15	$39.10
Purchase #6	$238.50	8.675%	$259.1899	$259.19	$259.20	$259.20
Purchase #7	$222.98	3.863%	$231.5937	$231.59	$231.60	$231.60
7 purchase totals =	$990.26		$1,074.0007	$1,074.00	$1,074.05	$1,074.10