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	$207.64	3.835%	$215.603	$215.60	$215.60	$215.60
Purchase #2	$141.31	6.719%	$150.8046	$150.80	$150.80	$150.80
Purchase #3	$90.94	4.844%	$95.3451	$95.35	$95.35	$95.30
Purchase #4	$250.62	3.702%	$259.898	$259.90	$259.90	$259.90
Purchase #5	$231.37	13.297%	$262.1353	$262.14	$262.15	$262.10
Purchase #6	$116.75	9.580%	$127.9347	$127.93	$127.95	$127.90
Purchase #7	$140.81	9.158%	$153.7054	$153.71	$153.70	$153.70
7 purchase totals =	$1,179.44		$1,265.4261	$1,265.43	$1,265.45	$1,265.30