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	$194.88	4.610%	$203.864	$203.86	$203.85	$203.90
Purchase #2	$100.26	6.775%	$107.0526	$107.05	$107.05	$107.10
Purchase #3	$160.67	9.741%	$176.3209	$176.32	$176.30	$176.30
Purchase #4	$79.45	11.453%	$88.5494	$88.55	$88.55	$88.50
Purchase #5	$184.46	6.767%	$196.9424	$196.94	$196.95	$196.90
Purchase #6	$166.91	5.151%	$175.5075	$175.51	$175.50	$175.50
Purchase #7	$158.59	13.259%	$179.6174	$179.62	$179.60	$179.60
7 purchase totals =	$1,045.22		$1,127.8542	$1,127.85	$1,127.80	$1,127.80