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	$42.43	4.248%	$44.2324	$44.23	$44.25	$44.20
Purchase #2	$223.49	10.319%	$246.5519	$246.55	$246.55	$246.60
Purchase #3	$188.73	10.724%	$208.9694	$208.97	$208.95	$209.00
Purchase #4	$180.55	5.359%	$190.2257	$190.23	$190.25	$190.20
Purchase #5	$104.72	9.448%	$114.6139	$114.61	$114.60	$114.60
Purchase #6	$75.85	3.203%	$78.2795	$78.28	$78.30	$78.30
Purchase #7	$176.69	10.152%	$194.6276	$194.63	$194.65	$194.60
7 purchase totals =	$992.46		$1,077.5004	$1,077.50	$1,077.55	$1,077.50