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	$119.38	10.705%	$132.1596	$132.16	$132.15	$132.20
Purchase #2	$56.83	13.242%	$64.3554	$64.36	$64.35	$64.40
Purchase #3	$175.89	8.170%	$190.2602	$190.26	$190.25	$190.30
Purchase #4	$184.42	10.138%	$203.1165	$203.12	$203.10	$203.10
Purchase #5	$41.59	8.663%	$45.1929	$45.19	$45.20	$45.20
Purchase #6	$211.43	7.432%	$227.1435	$227.14	$227.15	$227.10
Purchase #7	$174.85	13.684%	$198.7765	$198.78	$198.80	$198.80
7 purchase totals =	$964.39		$1,061.0046	$1,061.01	$1,061.00	$1,061.10