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	$194.74	9.513%	$213.2656	$213.27	$213.25	$213.30
Purchase #2	$26.64	8.650%	$28.9444	$28.94	$28.95	$28.90
Purchase #3	$221.31	11.684%	$247.1679	$247.17	$247.15	$247.20
Purchase #4	$113.31	12.205%	$127.1395	$127.14	$127.15	$127.10
Purchase #5	$90.90	11.267%	$101.1417	$101.14	$101.15	$101.10
Purchase #6	$83.52	10.176%	$92.019	$92.02	$92.00	$92.00
Purchase #7	$247.43	9.660%	$271.3317	$271.33	$271.35	$271.30
7 purchase totals =	$977.85		$1,081.0098	$1,081.01	$1,081.00	$1,080.90