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	$74.29	10.461%	$82.0615	$82.06	$82.05	$82.10
Purchase #2	$88.83	12.685%	$100.0981	$100.10	$100.10	$100.10
Purchase #3	$231.89	3.431%	$239.8461	$239.85	$239.85	$239.80
Purchase #4	$147.81	3.245%	$152.6064	$152.61	$152.60	$152.60
Purchase #5	$121.95	13.608%	$138.545	$138.55	$138.55	$138.50
Purchase #6	$206.89	7.579%	$222.5702	$222.57	$222.55	$222.60
Purchase #7	$75.32	5.216%	$79.2487	$79.25	$79.25	$79.20
7 purchase totals =	$946.98		$1,014.9760	$1,014.99	$1,014.95	$1,014.90