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	$196.72	4.598%	$205.7652	$205.77	$205.75	$205.80
Purchase #2	$159.27	9.861%	$174.9756	$174.98	$175.00	$175.00
Purchase #3	$46.45	13.731%	$52.828	$52.83	$52.85	$52.80
Purchase #4	$96.71	5.860%	$102.3772	$102.38	$102.40	$102.40
Purchase #5	$166.60	9.540%	$182.4936	$182.49	$182.50	$182.50
Purchase #6	$140.81	7.735%	$151.7017	$151.70	$151.70	$151.70
Purchase #7	$222.25	7.760%	$239.4966	$239.50	$239.50	$239.50
7 purchase totals =	$1,028.81		$1,109.6379	$1,109.65	$1,109.70	$1,109.70