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	$17.31	10.797%	$19.179	$19.18	$19.20	$19.20
Purchase #2	$76.32	8.250%	$82.6164	$82.62	$82.60	$82.60
Purchase #3	$119.86	5.866%	$126.891	$126.89	$126.90	$126.90
Purchase #4	$237.59	8.528%	$257.8517	$257.85	$257.85	$257.90
Purchase #5	$182.87	4.546%	$191.1833	$191.18	$191.20	$191.20
Purchase #6	$219.25	7.671%	$236.0687	$236.07	$236.05	$236.10
Purchase #7	$92.82	11.254%	$103.266	$103.27	$103.25	$103.30
7 purchase totals =	$946.02		$1,017.0561	$1,017.06	$1,017.05	$1,017.20