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	$100.41	7.311%	$107.751	$107.75	$107.75	$107.80
Purchase #2	$98.73	4.352%	$103.0267	$103.03	$103.05	$103.00
Purchase #3	$32.98	13.722%	$37.5055	$37.51	$37.50	$37.50
Purchase #4	$178.96	3.679%	$185.5439	$185.54	$185.55	$185.50
Purchase #5	$145.78	7.266%	$156.3724	$156.37	$156.35	$156.40
Purchase #6	$194.88	9.647%	$213.6801	$213.68	$213.70	$213.70
Purchase #7	$200.40	10.579%	$221.6003	$221.60	$221.60	$221.60
7 purchase totals =	$952.14		$1,025.4799	$1,025.48	$1,025.50	$1,025.50