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	$215.48	4.335%	$224.8211	$224.82	$224.80	$224.80
Purchase #2	$7.61	3.444%	$7.8721	$7.87	$7.85	$7.90
Purchase #3	$161.86	6.350%	$172.1381	$172.14	$172.15	$172.10
Purchase #4	$229.68	8.564%	$249.3498	$249.35	$249.35	$249.30
Purchase #5	$193.86	6.563%	$206.583	$206.58	$206.60	$206.60
Purchase #6	$84.52	9.474%	$92.5274	$92.53	$92.55	$92.50
Purchase #7	$172.58	3.154%	$178.0232	$178.02	$178.00	$178.00
7 purchase totals =	$1,065.59		$1,131.3147	$1,131.31	$1,131.30	$1,131.20