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	$207.56	7.326%	$222.7658	$222.77	$222.75	$222.80
Purchase #2	$59.86	3.322%	$61.8485	$61.85	$61.85	$61.80
Purchase #3	$175.56	5.615%	$185.4177	$185.42	$185.40	$185.40
Purchase #4	$129.60	4.571%	$135.524	$135.52	$135.50	$135.50
Purchase #5	$54.31	9.128%	$59.2674	$59.27	$59.25	$59.30
Purchase #6	$64.37	5.325%	$67.7977	$67.80	$67.80	$67.80
Purchase #7	$34.84	11.318%	$38.7832	$38.78	$38.80	$38.80
7 purchase totals =	$726.10		$771.4043	$771.41	$771.35	$771.40