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	$211.79	10.580%	$234.1974	$234.20	$234.20	$234.20
Purchase #2	$24.70	7.104%	$26.4547	$26.45	$26.45	$26.50
Purchase #3	$111.45	6.682%	$118.8971	$118.90	$118.90	$118.90
Purchase #4	$138.34	10.151%	$152.3829	$152.38	$152.40	$152.40
Purchase #5	$229.90	11.743%	$256.8972	$256.90	$256.90	$256.90
Purchase #6	$108.40	13.666%	$123.2139	$123.21	$123.20	$123.20
Purchase #7	$148.56	9.440%	$162.5841	$162.58	$162.60	$162.60
7 purchase totals =	$973.14		$1,074.6273	$1,074.62	$1,074.65	$1,074.70