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	$181.38	5.454%	$191.2725	$191.27	$191.25	$191.30
Purchase #2	$82.44	10.130%	$90.7912	$90.79	$90.80	$90.80
Purchase #3	$166.31	11.833%	$185.9895	$185.99	$186.00	$186.00
Purchase #4	$138.51	7.370%	$148.7182	$148.72	$148.70	$148.70
Purchase #5	$113.92	8.569%	$123.6818	$123.68	$123.70	$123.70
Purchase #6	$117.36	9.837%	$128.9047	$128.90	$128.90	$128.90
Purchase #7	$127.70	13.509%	$144.951	$144.95	$144.95	$145.00
7 purchase totals =	$927.62		$1,014.3089	$1,014.30	$1,014.30	$1,014.40