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	$247.25	4.714%	$258.9054	$258.91	$258.90	$258.90
Purchase #2	$165.97	5.676%	$175.3905	$175.39	$175.40	$175.40
Purchase #3	$33.86	9.587%	$37.1062	$37.11	$37.10	$37.10
Purchase #4	$204.83	3.239%	$211.4644	$211.46	$211.45	$211.50
Purchase #5	$144.84	4.789%	$151.7764	$151.78	$151.80	$151.80
Purchase #6	$178.71	5.269%	$188.1262	$188.13	$188.15	$188.10
Purchase #7	$142.82	13.724%	$162.4206	$162.42	$162.40	$162.40
7 purchase totals =	$1,118.28		$1,185.1897	$1,185.20	$1,185.20	$1,185.20