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	$89.49	8.336%	$96.9499	$96.95	$96.95	$96.90
Purchase #2	$127.59	4.152%	$132.8875	$132.89	$132.90	$132.90
Purchase #3	$31.80	7.297%	$34.1204	$34.12	$34.10	$34.10
Purchase #4	$241.65	9.734%	$265.1722	$265.17	$265.15	$265.20
Purchase #5	$168.62	9.665%	$184.9171	$184.92	$184.90	$184.90
Purchase #6	$116.96	5.566%	$123.47	$123.47	$123.45	$123.50
Purchase #7	$230.71	10.701%	$255.3983	$255.40	$255.40	$255.40
7 purchase totals =	$1,006.82		$1,092.9154	$1,092.92	$1,092.85	$1,092.90