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	$148.76	6.515%	$158.4517	$158.45	$158.45	$158.50
Purchase #2	$91.83	5.380%	$96.7705	$96.77	$96.75	$96.80
Purchase #3	$213.66	4.850%	$224.0225	$224.02	$224.00	$224.00
Purchase #4	$224.60	5.652%	$237.2944	$237.29	$237.30	$237.30
Purchase #5	$179.82	11.378%	$200.2799	$200.28	$200.30	$200.30
Purchase #6	$106.80	4.745%	$111.8677	$111.87	$111.85	$111.90
Purchase #7	$79.48	13.444%	$90.1653	$90.17	$90.15	$90.20
7 purchase totals =	$1,044.95		$1,118.8520	$1,118.85	$1,118.80	$1,119.00