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	$178.48	10.346%	$196.9455	$196.95	$196.95	$196.90
Purchase #2	$171.26	8.712%	$186.1802	$186.18	$186.20	$186.20
Purchase #3	$181.52	10.419%	$200.4326	$200.43	$200.45	$200.40
Purchase #4	$86.81	4.689%	$90.8805	$90.88	$90.90	$90.90
Purchase #5	$36.41	4.239%	$37.9534	$37.95	$37.95	$38.00
Purchase #6	$213.84	12.821%	$241.2564	$241.26	$241.25	$241.30
Purchase #7	$59.84	8.585%	$64.9773	$64.98	$65.00	$65.00
7 purchase totals =	$928.16		$1,018.6259	$1,018.63	$1,018.70	$1,018.70