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	$200.51	11.396%	$223.3601	$223.36	$223.35	$223.40
Purchase #2	$20.78	7.353%	$22.308	$22.31	$22.30	$22.30
Purchase #3	$207.96	13.270%	$235.5563	$235.56	$235.55	$235.60
Purchase #4	$82.89	9.551%	$90.8068	$90.81	$90.80	$90.80
Purchase #5	$221.89	13.682%	$252.249	$252.25	$252.25	$252.20
Purchase #6	$47.81	6.439%	$50.8885	$50.89	$50.90	$50.90
Purchase #7	$225.48	7.763%	$242.984	$242.98	$243.00	$243.00
7 purchase totals =	$1,007.32		$1,118.1527	$1,118.16	$1,118.15	$1,118.20