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	$196.84	6.601%	$209.8334	$209.83	$209.85	$209.80
Purchase #2	$199.46	11.526%	$222.4498	$222.45	$222.45	$222.40
Purchase #3	$242.57	12.123%	$271.9768	$271.98	$272.00	$272.00
Purchase #4	$166.96	11.608%	$186.3407	$186.34	$186.35	$186.30
Purchase #5	$81.31	11.435%	$90.6078	$90.61	$90.60	$90.60
Purchase #6	$168.55	3.523%	$174.488	$174.49	$174.50	$174.50
Purchase #7	$151.92	3.748%	$157.614	$157.61	$157.60	$157.60
7 purchase totals =	$1,207.61		$1,313.3105	$1,313.31	$1,313.35	$1,313.20