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	$182.58	7.691%	$196.6222	$196.62	$196.60	$196.60
Purchase #2	$32.58	13.759%	$37.0627	$37.06	$37.05	$37.10
Purchase #3	$160.93	9.256%	$175.8257	$175.83	$175.85	$175.80
Purchase #4	$33.98	11.341%	$37.8337	$37.83	$37.85	$37.80
Purchase #5	$235.70	7.393%	$253.1253	$253.13	$253.15	$253.10
Purchase #6	$130.51	4.231%	$136.0319	$136.03	$136.05	$136.00
Purchase #7	$241.80	6.873%	$258.4189	$258.42	$258.40	$258.40
7 purchase totals =	$1,018.08		$1,094.9204	$1,094.92	$1,094.95	$1,094.80