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	$41.27	10.578%	$45.6355	$45.64	$45.65	$45.60
Purchase #2	$173.86	13.299%	$196.9816	$196.98	$197.00	$197.00
Purchase #3	$73.90	7.728%	$79.611	$79.61	$79.60	$79.60
Purchase #4	$40.53	13.836%	$46.1377	$46.14	$46.15	$46.10
Purchase #5	$241.97	3.490%	$250.4148	$250.41	$250.40	$250.40
Purchase #6	$91.88	8.239%	$99.45	$99.45	$99.45	$99.50
Purchase #7	$102.47	11.433%	$114.1854	$114.19	$114.20	$114.20
7 purchase totals =	$765.88		$832.4160	$832.42	$832.45	$832.40