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	$22.58	4.411%	$23.576	$23.58	$23.60	$23.60
Purchase #2	$203.66	9.714%	$223.4435	$223.44	$223.45	$223.40
Purchase #3	$197.57	6.826%	$211.0561	$211.06	$211.05	$211.10
Purchase #4	$160.45	13.130%	$181.5171	$181.52	$181.50	$181.50
Purchase #5	$86.76	4.177%	$90.384	$90.38	$90.40	$90.40
Purchase #6	$248.39	7.593%	$267.2503	$267.25	$267.25	$267.30
Purchase #7	$99.44	10.287%	$109.6694	$109.67	$109.65	$109.70
7 purchase totals =	$1,018.85		$1,106.8964	$1,106.90	$1,106.90	$1,107.00