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	$145.89	3.803%	$151.4382	$151.44	$151.45	$151.40
Purchase #2	$130.79	5.232%	$137.6329	$137.63	$137.65	$137.60
Purchase #3	$57.48	5.423%	$60.5971	$60.60	$60.60	$60.60
Purchase #4	$73.36	6.342%	$78.0125	$78.01	$78.00	$78.00
Purchase #5	$229.55	7.283%	$246.2681	$246.27	$246.25	$246.30
Purchase #6	$164.83	9.275%	$180.118	$180.12	$180.10	$180.10
Purchase #7	$165.91	10.256%	$182.9257	$182.93	$182.95	$182.90
7 purchase totals =	$967.81		$1,036.9925	$1,037.00	$1,037.00	$1,036.90