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	$232.25	10.357%	$256.3041	$256.30	$256.30	$256.30
Purchase #2	$70.63	7.280%	$75.7719	$75.77	$75.75	$75.80
Purchase #3	$123.64	6.320%	$131.454	$131.45	$131.45	$131.50
Purchase #4	$82.47	3.775%	$85.5832	$85.58	$85.60	$85.60
Purchase #5	$238.39	10.531%	$263.4949	$263.49	$263.50	$263.50
Purchase #6	$97.38	7.721%	$104.8987	$104.90	$104.90	$104.90
Purchase #7	$249.98	3.325%	$258.2918	$258.29	$258.30	$258.30
7 purchase totals =	$1,094.74		$1,175.7986	$1,175.78	$1,175.80	$1,175.90