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	$216.25	4.444%	$225.8602	$225.86	$225.85	$225.90
Purchase #2	$219.26	11.680%	$244.8696	$244.87	$244.85	$244.90
Purchase #3	$238.73	10.586%	$264.002	$264.00	$264.00	$264.00
Purchase #4	$96.97	3.611%	$100.4716	$100.47	$100.45	$100.50
Purchase #5	$175.77	11.210%	$195.4738	$195.47	$195.45	$195.50
Purchase #6	$199.40	7.621%	$214.5963	$214.60	$214.60	$214.60
Purchase #7	$100.34	11.416%	$111.7948	$111.79	$111.80	$111.80
7 purchase totals =	$1,246.72		$1,357.0683	$1,357.06	$1,357.00	$1,357.20