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	$212.96	6.869%	$227.5882	$227.59	$227.60	$227.60
Purchase #2	$118.96	10.678%	$131.6625	$131.66	$131.65	$131.70
Purchase #3	$223.80	4.774%	$234.4842	$234.48	$234.50	$234.50
Purchase #4	$211.38	12.798%	$238.4324	$238.43	$238.45	$238.40
Purchase #5	$40.28	5.774%	$42.6058	$42.61	$42.60	$42.60
Purchase #6	$65.86	4.116%	$68.5708	$68.57	$68.55	$68.60
Purchase #7	$214.92	4.816%	$225.2705	$225.27	$225.25	$225.30
7 purchase totals =	$1,088.16		$1,168.6144	$1,168.61	$1,168.60	$1,168.70