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	$147.46	10.767%	$163.337	$163.34	$163.35	$163.30
Purchase #2	$155.29	10.739%	$171.9666	$171.97	$171.95	$172.00
Purchase #3	$154.95	10.537%	$171.2771	$171.28	$171.30	$171.30
Purchase #4	$177.89	4.860%	$186.5355	$186.54	$186.55	$186.50
Purchase #5	$227.94	12.212%	$255.776	$255.78	$255.80	$255.80
Purchase #6	$54.31	13.270%	$61.5169	$61.52	$61.50	$61.50
Purchase #7	$132.62	3.213%	$136.8811	$136.88	$136.90	$136.90
7 purchase totals =	$1,050.46		$1,147.2902	$1,147.31	$1,147.35	$1,147.30