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	$181.97	10.216%	$200.5601	$200.56	$200.55	$200.60
Purchase #2	$213.54	10.182%	$235.2826	$235.28	$235.30	$235.30
Purchase #3	$240.71	10.702%	$266.4708	$266.47	$266.45	$266.50
Purchase #4	$7.44	12.621%	$8.379	$8.38	$8.40	$8.40
Purchase #5	$92.95	7.848%	$100.2447	$100.24	$100.25	$100.20
Purchase #6	$153.63	10.103%	$169.1512	$169.15	$169.15	$169.20
Purchase #7	$96.78	13.536%	$109.8801	$109.88	$109.90	$109.90
7 purchase totals =	$987.02		$1,089.9685	$1,089.96	$1,090.00	$1,090.10