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	$234.72	4.365%	$244.9655	$244.97	$244.95	$245.00
Purchase #2	$136.29	4.534%	$142.4694	$142.47	$142.45	$142.50
Purchase #3	$226.95	6.453%	$241.5951	$241.60	$241.60	$241.60
Purchase #4	$153.35	8.274%	$166.0382	$166.04	$166.05	$166.00
Purchase #5	$208.78	10.278%	$230.2384	$230.24	$230.25	$230.20
Purchase #6	$57.25	4.616%	$59.8927	$59.89	$59.90	$59.90
Purchase #7	$167.87	4.739%	$175.8254	$175.83	$175.85	$175.80
7 purchase totals =	$1,185.21		$1,261.0247	$1,261.04	$1,261.05	$1,261.00