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	$191.66	10.513%	$211.8092	$211.81	$211.80	$211.80
Purchase #2	$225.71	10.758%	$249.9919	$249.99	$250.00	$250.00
Purchase #3	$207.30	9.849%	$227.717	$227.72	$227.70	$227.70
Purchase #4	$72.47	13.769%	$82.4484	$82.45	$82.45	$82.40
Purchase #5	$115.85	10.399%	$127.8972	$127.90	$127.90	$127.90
Purchase #6	$52.27	6.187%	$55.5039	$55.50	$55.50	$55.50
Purchase #7	$194.78	10.156%	$214.5619	$214.56	$214.55	$214.60
7 purchase totals =	$1,060.04		$1,169.9295	$1,169.93	$1,169.90	$1,169.90