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	$158.29	5.483%	$166.969	$166.97	$166.95	$167.00
Purchase #2	$104.27	6.513%	$111.0611	$111.06	$111.05	$111.10
Purchase #3	$156.70	12.788%	$176.7388	$176.74	$176.75	$176.70
Purchase #4	$160.41	6.361%	$170.6137	$170.61	$170.60	$170.60
Purchase #5	$100.70	11.773%	$112.5554	$112.56	$112.55	$112.60
Purchase #6	$226.78	7.646%	$244.1196	$244.12	$244.10	$244.10
Purchase #7	$109.40	3.523%	$113.2542	$113.25	$113.25	$113.30
7 purchase totals =	$1,016.55		$1,095.3118	$1,095.31	$1,095.25	$1,095.40