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	$80.63	6.757%	$86.0782	$86.08	$86.10	$86.10
Purchase #2	$193.42	5.499%	$204.0562	$204.06	$204.05	$204.10
Purchase #3	$15.94	13.538%	$18.098	$18.10	$18.10	$18.10
Purchase #4	$231.79	13.852%	$263.8976	$263.90	$263.90	$263.90
Purchase #5	$67.70	6.640%	$72.1953	$72.20	$72.20	$72.20
Purchase #6	$222.93	4.867%	$233.78	$233.78	$233.80	$233.80
Purchase #7	$129.61	6.640%	$138.2161	$138.22	$138.20	$138.20
7 purchase totals =	$942.02		$1,016.3214	$1,016.34	$1,016.35	$1,016.40