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	$61.33	13.804%	$69.796	$69.80	$69.80	$69.80
Purchase #2	$186.59	4.268%	$194.5537	$194.55	$194.55	$194.60
Purchase #3	$171.62	10.271%	$189.2471	$189.25	$189.25	$189.20
Purchase #4	$219.44	6.581%	$233.8813	$233.88	$233.90	$233.90
Purchase #5	$123.72	12.225%	$138.8448	$138.84	$138.85	$138.80
Purchase #6	$184.90	6.291%	$196.5321	$196.53	$196.55	$196.50
Purchase #7	$184.98	13.825%	$210.5535	$210.55	$210.55	$210.60
7 purchase totals =	$1,132.58		$1,233.4085	$1,233.40	$1,233.45	$1,233.40