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	$198.95	10.376%	$219.5931	$219.59	$219.60	$219.60
Purchase #2	$40.92	6.518%	$43.5872	$43.59	$43.60	$43.60
Purchase #3	$118.95	10.512%	$131.454	$131.45	$131.45	$131.50
Purchase #4	$198.81	9.324%	$217.347	$217.35	$217.35	$217.30
Purchase #5	$141.27	7.244%	$151.5036	$151.50	$151.50	$151.50
Purchase #6	$144.69	6.843%	$154.5911	$154.59	$154.60	$154.60
Purchase #7	$233.82	13.144%	$264.5533	$264.55	$264.55	$264.60
7 purchase totals =	$1,077.41		$1,182.6293	$1,182.62	$1,182.65	$1,182.70