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	$118.83	9.619%	$130.2603	$130.26	$130.25	$130.30
Purchase #2	$145.35	4.657%	$152.1189	$152.12	$152.10	$152.10
Purchase #3	$148.29	13.624%	$168.493	$168.49	$168.50	$168.50
Purchase #4	$118.95	3.481%	$123.0906	$123.09	$123.10	$123.10
Purchase #5	$112.42	4.556%	$117.5419	$117.54	$117.55	$117.50
Purchase #6	$107.90	7.504%	$115.9968	$116.00	$116.00	$116.00
Purchase #7	$214.77	7.818%	$231.5607	$231.56	$231.55	$231.60
7 purchase totals =	$966.51		$1,039.0622	$1,039.06	$1,039.05	$1,039.10