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	$241.95	8.731%	$263.0747	$263.07	$263.05	$263.10
Purchase #2	$158.35	11.190%	$176.0694	$176.07	$176.05	$176.10
Purchase #3	$99.34	10.156%	$109.429	$109.43	$109.45	$109.40
Purchase #4	$59.73	3.246%	$61.6688	$61.67	$61.65	$61.70
Purchase #5	$237.52	9.388%	$259.8184	$259.82	$259.80	$259.80
Purchase #6	$64.81	4.168%	$67.5113	$67.51	$67.50	$67.50
Purchase #7	$114.41	4.223%	$119.2415	$119.24	$119.25	$119.20
7 purchase totals =	$976.11		$1,056.8131	$1,056.81	$1,056.75	$1,056.80