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	$173.54	13.394%	$196.7839	$196.78	$196.80	$196.80
Purchase #2	$10.52	5.576%	$11.1066	$11.11	$11.10	$11.10
Purchase #3	$244.63	7.455%	$262.8672	$262.87	$262.85	$262.90
Purchase #4	$248.81	13.436%	$282.2401	$282.24	$282.25	$282.20
Purchase #5	$82.34	12.172%	$92.3624	$92.36	$92.35	$92.40
Purchase #6	$209.47	6.371%	$222.8153	$222.82	$222.80	$222.80
Purchase #7	$218.83	5.683%	$231.2661	$231.27	$231.25	$231.30
7 purchase totals =	$1,188.14		$1,299.4416	$1,299.45	$1,299.40	$1,299.50