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	$212.50	9.677%	$233.0636	$233.06	$233.05	$233.10
Purchase #2	$154.45	7.436%	$165.9349	$165.93	$165.95	$165.90
Purchase #3	$54.76	10.596%	$60.5624	$60.56	$60.55	$60.60
Purchase #4	$35.95	7.169%	$38.5273	$38.53	$38.55	$38.50
Purchase #5	$223.39	12.260%	$250.7776	$250.78	$250.80	$250.80
Purchase #6	$65.32	11.552%	$72.8658	$72.87	$72.85	$72.90
Purchase #7	$190.38	11.256%	$211.8092	$211.81	$211.80	$211.80
7 purchase totals =	$936.75		$1,033.5408	$1,033.54	$1,033.55	$1,033.60