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	$211.84	7.291%	$227.2853	$227.29	$227.30	$227.30
Purchase #2	$12.82	9.191%	$13.9983	$14.00	$14.00	$14.00
Purchase #3	$53.92	5.870%	$57.0851	$57.09	$57.10	$57.10
Purchase #4	$222.94	7.147%	$238.8735	$238.87	$238.85	$238.90
Purchase #5	$180.50	10.569%	$199.577	$199.58	$199.60	$199.60
Purchase #6	$17.56	3.788%	$18.2252	$18.23	$18.25	$18.20
Purchase #7	$68.73	13.581%	$78.0642	$78.06	$78.05	$78.10
7 purchase totals =	$768.31		$833.1086	$833.12	$833.15	$833.20