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	$192.43	13.843%	$219.0681	$219.07	$219.05	$219.10
Purchase #2	$236.48	4.670%	$247.5236	$247.52	$247.50	$247.50
Purchase #3	$203.94	4.821%	$213.7719	$213.77	$213.75	$213.80
Purchase #4	$34.94	6.525%	$37.2198	$37.22	$37.20	$37.20
Purchase #5	$132.42	9.854%	$145.4687	$145.47	$145.45	$145.50
Purchase #6	$114.52	10.822%	$126.9134	$126.91	$126.90	$126.90
Purchase #7	$98.91	4.782%	$103.6399	$103.64	$103.65	$103.60
7 purchase totals =	$1,013.64		$1,093.6054	$1,093.60	$1,093.50	$1,093.60