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	$82.31	8.767%	$89.5261	$89.53	$89.55	$89.50
Purchase #2	$238.47	6.753%	$254.5739	$254.57	$254.55	$254.60
Purchase #3	$123.67	3.259%	$127.7004	$127.70	$127.70	$127.70
Purchase #4	$175.25	3.308%	$181.0473	$181.05	$181.05	$181.00
Purchase #5	$215.56	10.231%	$237.6139	$237.61	$237.60	$237.60
Purchase #6	$91.94	10.832%	$101.8989	$101.90	$101.90	$101.90
Purchase #7	$70.68	8.428%	$76.6369	$76.64	$76.65	$76.60
7 purchase totals =	$997.88		$1,068.9974	$1,069.00	$1,069.00	$1,068.90