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	$212.71	4.806%	$222.9328	$222.93	$222.95	$222.90
Purchase #2	$71.69	9.244%	$78.317	$78.32	$78.30	$78.30
Purchase #3	$182.91	13.791%	$208.1351	$208.14	$208.15	$208.10
Purchase #4	$21.70	10.449%	$23.9674	$23.97	$23.95	$24.00
Purchase #5	$53.25	10.561%	$58.8737	$58.87	$58.85	$58.90
Purchase #6	$233.40	3.829%	$242.3369	$242.34	$242.35	$242.30
Purchase #7	$129.76	11.105%	$144.1698	$144.17	$144.15	$144.20
7 purchase totals =	$905.42		$978.7327	$978.74	$978.70	$978.70