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	$106.39	7.270%	$114.1246	$114.12	$114.10	$114.10
Purchase #2	$109.63	5.452%	$115.607	$115.61	$115.60	$115.60
Purchase #3	$243.49	7.846%	$262.5942	$262.59	$262.60	$262.60
Purchase #4	$196.50	9.187%	$214.5525	$214.55	$214.55	$214.60
Purchase #5	$59.28	3.534%	$61.375	$61.38	$61.40	$61.40
Purchase #6	$10.88	5.845%	$11.5159	$11.52	$11.50	$11.50
Purchase #7	$214.31	9.683%	$235.0616	$235.06	$235.05	$235.10
7 purchase totals =	$940.48		$1,014.8308	$1,014.83	$1,014.80	$1,014.90