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	$192.50	7.734%	$207.388	$207.39	$207.40	$207.40
Purchase #2	$55.89	5.673%	$59.0606	$59.06	$59.05	$59.10
Purchase #3	$37.90	9.378%	$41.4543	$41.45	$41.45	$41.50
Purchase #4	$113.53	5.631%	$119.9229	$119.92	$119.90	$119.90
Purchase #5	$200.66	4.233%	$209.1539	$209.15	$209.15	$209.20
Purchase #6	$106.39	6.511%	$113.3171	$113.32	$113.30	$113.30
Purchase #7	$240.72	11.591%	$268.6219	$268.62	$268.60	$268.60
7 purchase totals =	$947.59		$1,018.9187	$1,018.91	$1,018.85	$1,019.00