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	$213.77	11.542%	$238.4433	$238.44	$238.45	$238.40
Purchase #2	$204.72	5.727%	$216.4443	$216.44	$216.45	$216.40
Purchase #3	$231.60	6.123%	$245.7809	$245.78	$245.80	$245.80
Purchase #4	$216.93	11.284%	$241.4084	$241.41	$241.40	$241.40
Purchase #5	$133.76	9.595%	$146.5943	$146.59	$146.60	$146.60
Purchase #6	$86.75	9.492%	$94.9843	$94.98	$95.00	$95.00
Purchase #7	$211.94	5.624%	$223.8595	$223.86	$223.85	$223.90
7 purchase totals =	$1,299.47		$1,407.5150	$1,407.50	$1,407.55	$1,407.50