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	$142.61	11.167%	$158.5353	$158.54	$158.55	$158.50
Purchase #2	$124.79	6.585%	$133.0074	$133.01	$133.00	$133.00
Purchase #3	$120.25	5.625%	$127.0141	$127.01	$127.00	$127.00
Purchase #4	$202.40	11.496%	$225.6679	$225.67	$225.65	$225.70
Purchase #5	$218.63	8.660%	$237.5634	$237.56	$237.55	$237.60
Purchase #6	$38.93	6.142%	$41.3211	$41.32	$41.30	$41.30
Purchase #7	$27.95	12.103%	$31.3328	$31.33	$31.35	$31.30
7 purchase totals =	$875.56		$954.4420	$954.44	$954.40	$954.40