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	$178.25	11.400%	$198.5705	$198.57	$198.55	$198.60
Purchase #2	$186.54	13.680%	$212.0587	$212.06	$212.05	$212.10
Purchase #3	$56.62	5.468%	$59.716	$59.72	$59.70	$59.70
Purchase #4	$118.98	6.140%	$126.2854	$126.29	$126.30	$126.30
Purchase #5	$70.54	10.391%	$77.8698	$77.87	$77.85	$77.90
Purchase #6	$207.60	4.195%	$216.3088	$216.31	$216.30	$216.30
Purchase #7	$166.90	12.641%	$187.9978	$188.00	$188.00	$188.00
7 purchase totals =	$985.43		$1,078.8070	$1,078.82	$1,078.75	$1,078.90