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	$77.80	10.492%	$85.9628	$85.96	$85.95	$86.00
Purchase #2	$88.59	13.126%	$100.2183	$100.22	$100.20	$100.20
Purchase #3	$204.63	4.555%	$213.9509	$213.95	$213.95	$214.00
Purchase #4	$152.96	6.161%	$162.3839	$162.38	$162.40	$162.40
Purchase #5	$97.56	6.681%	$104.078	$104.08	$104.10	$104.10
Purchase #6	$145.72	10.594%	$161.1576	$161.16	$161.15	$161.20
Purchase #7	$240.96	11.182%	$267.9041	$267.90	$267.90	$267.90
7 purchase totals =	$1,008.22		$1,095.6556	$1,095.65	$1,095.65	$1,095.80