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	$58.88	5.195%	$61.9388	$61.94	$61.95	$61.90
Purchase #2	$250.83	4.582%	$262.323	$262.32	$262.30	$262.30
Purchase #3	$35.73	9.191%	$39.0139	$39.01	$39.00	$39.00
Purchase #4	$228.73	5.543%	$241.4085	$241.41	$241.40	$241.40
Purchase #5	$158.61	13.145%	$179.4593	$179.46	$179.45	$179.50
Purchase #6	$136.98	6.295%	$145.6029	$145.60	$145.60	$145.60
Purchase #7	$178.46	3.324%	$184.392	$184.39	$184.40	$184.40
7 purchase totals =	$1,048.22		$1,114.1384	$1,114.13	$1,114.10	$1,114.10