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	$189.68	6.809%	$202.5953	$202.60	$202.60	$202.60
Purchase #2	$33.75	11.108%	$37.499	$37.50	$37.50	$37.50
Purchase #3	$183.30	13.747%	$208.4983	$208.50	$208.50	$208.50
Purchase #4	$53.30	4.126%	$55.4992	$55.50	$55.50	$55.50
Purchase #5	$78.62	10.661%	$87.0017	$87.00	$87.00	$87.00
Purchase #6	$232.42	4.577%	$243.0579	$243.06	$243.05	$243.10
Purchase #7	$233.82	12.481%	$263.0031	$263.00	$263.00	$263.00
7 purchase totals =	$1,004.89		$1,097.1545	$1,097.16	$1,097.15	$1,097.20