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	$61.90	9.272%	$67.6394	$67.64	$67.65	$67.60
Purchase #2	$77.82	3.500%	$80.5437	$80.54	$80.55	$80.50
Purchase #3	$103.94	3.759%	$107.8471	$107.85	$107.85	$107.80
Purchase #4	$137.73	13.709%	$156.6114	$156.61	$156.60	$156.60
Purchase #5	$167.31	5.276%	$176.1373	$176.14	$176.15	$176.10
Purchase #6	$200.81	3.458%	$207.754	$207.75	$207.75	$207.80
Purchase #7	$193.51	13.819%	$220.2511	$220.25	$220.25	$220.30
7 purchase totals =	$943.02		$1,016.7840	$1,016.78	$1,016.80	$1,016.70