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	$164.93	6.585%	$175.7906	$175.79	$175.80	$175.80
Purchase #2	$25.81	10.496%	$28.519	$28.52	$28.50	$28.50
Purchase #3	$218.97	11.608%	$244.388	$244.39	$244.40	$244.40
Purchase #4	$231.45	12.826%	$261.1358	$261.14	$261.15	$261.10
Purchase #5	$85.53	4.810%	$89.644	$89.64	$89.65	$89.60
Purchase #6	$63.80	5.245%	$67.1463	$67.15	$67.15	$67.10
Purchase #7	$226.45	13.501%	$257.023	$257.02	$257.00	$257.00
7 purchase totals =	$1,016.94		$1,123.6467	$1,123.65	$1,123.65	$1,123.50