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	$116.50	7.573%	$125.3225	$125.32	$125.30	$125.30
Purchase #2	$94.39	9.259%	$103.1296	$103.13	$103.15	$103.10
Purchase #3	$68.42	4.651%	$71.6022	$71.60	$71.60	$71.60
Purchase #4	$193.69	10.547%	$214.1185	$214.12	$214.10	$214.10
Purchase #5	$126.40	8.431%	$137.0568	$137.06	$137.05	$137.10
Purchase #6	$45.64	4.120%	$47.5204	$47.52	$47.50	$47.50
Purchase #7	$50.52	6.685%	$53.8973	$53.90	$53.90	$53.90
7 purchase totals =	$695.56		$752.6473	$752.65	$752.60	$752.60