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	$69.47	4.484%	$72.585	$72.59	$72.60	$72.60
Purchase #2	$63.30	4.636%	$66.2346	$66.23	$66.25	$66.20
Purchase #3	$77.28	12.364%	$86.8349	$86.83	$86.85	$86.80
Purchase #4	$207.51	4.342%	$216.5201	$216.52	$216.50	$216.50
Purchase #5	$103.35	8.309%	$111.9374	$111.94	$111.95	$111.90
Purchase #6	$153.34	8.608%	$166.5395	$166.54	$166.55	$166.50
Purchase #7	$57.93	6.220%	$61.5332	$61.53	$61.55	$61.50
7 purchase totals =	$732.18		$782.1847	$782.18	$782.25	$782.00