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	$147.58	12.695%	$166.3153	$166.32	$166.30	$166.30
Purchase #2	$13.73	4.323%	$14.3235	$14.32	$14.30	$14.30
Purchase #3	$68.38	13.373%	$77.5245	$77.52	$77.50	$77.50
Purchase #4	$237.81	10.430%	$262.6136	$262.61	$262.60	$262.60
Purchase #5	$248.88	6.434%	$264.8929	$264.89	$264.90	$264.90
Purchase #6	$72.67	6.738%	$77.5665	$77.57	$77.55	$77.60
Purchase #7	$144.56	4.832%	$151.5451	$151.55	$151.55	$151.50
7 purchase totals =	$933.61		$1,014.7814	$1,014.78	$1,014.70	$1,014.70