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	$211.65	9.327%	$231.3906	$231.39	$231.40	$231.40
Purchase #2	$59.38	4.394%	$61.9892	$61.99	$62.00	$62.00
Purchase #3	$29.68	4.851%	$31.1198	$31.12	$31.10	$31.10
Purchase #4	$181.29	10.789%	$200.8494	$200.85	$200.85	$200.80
Purchase #5	$202.63	10.487%	$223.8798	$223.88	$223.90	$223.90
Purchase #6	$214.84	9.824%	$235.9459	$235.95	$235.95	$235.90
Purchase #7	$82.81	8.572%	$89.9085	$89.91	$89.90	$89.90
7 purchase totals =	$982.28		$1,075.0832	$1,075.09	$1,075.10	$1,075.00