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	$192.33	9.368%	$210.3475	$210.35	$210.35	$210.30
Purchase #2	$100.87	4.345%	$105.2528	$105.25	$105.25	$105.30
Purchase #3	$95.53	9.323%	$104.4363	$104.44	$104.45	$104.40
Purchase #4	$107.60	5.325%	$113.3297	$113.33	$113.35	$113.30
Purchase #5	$149.58	9.838%	$164.2957	$164.30	$164.30	$164.30
Purchase #6	$147.93	9.863%	$162.5203	$162.52	$162.50	$162.50
Purchase #7	$156.79	3.243%	$161.8747	$161.87	$161.85	$161.90
7 purchase totals =	$950.63		$1,022.0570	$1,022.06	$1,022.05	$1,022.00