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	$140.92	7.511%	$151.5045	$151.50	$151.50	$151.50
Purchase #2	$104.66	6.331%	$111.286	$111.29	$111.30	$111.30
Purchase #3	$157.79	6.109%	$167.4294	$167.43	$167.45	$167.40
Purchase #4	$28.79	7.732%	$31.016	$31.02	$31.00	$31.00
Purchase #5	$14.86	4.675%	$15.5547	$15.55	$15.55	$15.60
Purchase #6	$160.40	10.247%	$176.8362	$176.84	$176.85	$176.80
Purchase #7	$92.87	6.167%	$98.5973	$98.60	$98.60	$98.60
7 purchase totals =	$700.29		$752.2241	$752.23	$752.25	$752.20