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	$132.95	11.660%	$148.452	$148.45	$148.45	$148.50
Purchase #2	$35.77	4.648%	$37.4326	$37.43	$37.45	$37.40
Purchase #3	$131.69	9.661%	$144.4126	$144.41	$144.40	$144.40
Purchase #4	$145.37	4.826%	$152.3856	$152.39	$152.40	$152.40
Purchase #5	$233.96	5.268%	$246.285	$246.29	$246.30	$246.30
Purchase #6	$241.88	8.289%	$261.9294	$261.93	$261.95	$261.90
Purchase #7	$179.89	10.406%	$198.6094	$198.61	$198.60	$198.60
7 purchase totals =	$1,101.51		$1,189.5066	$1,189.51	$1,189.55	$1,189.50