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	$94.97	5.483%	$100.1772	$100.18	$100.20	$100.20
Purchase #2	$15.31	4.155%	$15.9461	$15.95	$15.95	$15.90
Purchase #3	$123.95	8.485%	$134.4672	$134.47	$134.45	$134.50
Purchase #4	$184.92	7.851%	$199.4381	$199.44	$199.45	$199.40
Purchase #5	$148.32	11.611%	$165.5414	$165.54	$165.55	$165.50
Purchase #6	$212.78	9.560%	$233.1218	$233.12	$233.10	$233.10
Purchase #7	$183.77	6.702%	$196.0863	$196.09	$196.10	$196.10
7 purchase totals =	$964.02		$1,044.7781	$1,044.79	$1,044.80	$1,044.70