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	$233.75	5.252%	$246.0266	$246.03	$246.05	$246.00
Purchase #2	$20.59	4.104%	$21.435	$21.44	$21.45	$21.40
Purchase #3	$223.83	9.606%	$245.3311	$245.33	$245.35	$245.30
Purchase #4	$118.25	6.228%	$125.6146	$125.61	$125.60	$125.60
Purchase #5	$32.43	4.767%	$33.9759	$33.98	$34.00	$34.00
Purchase #6	$228.80	13.789%	$260.3492	$260.35	$260.35	$260.30
Purchase #7	$223.77	6.624%	$238.5925	$238.59	$238.60	$238.60
7 purchase totals =	$1,081.42		$1,171.3249	$1,171.33	$1,171.40	$1,171.20