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	$177.40	8.589%	$192.6369	$192.64	$192.65	$192.60
Purchase #2	$214.87	13.663%	$244.2277	$244.23	$244.25	$244.20
Purchase #3	$31.60	6.305%	$33.5924	$33.59	$33.60	$33.60
Purchase #4	$43.43	7.579%	$46.7216	$46.72	$46.70	$46.70
Purchase #5	$50.35	7.214%	$53.9822	$53.98	$54.00	$54.00
Purchase #6	$105.33	12.280%	$118.2645	$118.26	$118.25	$118.30
Purchase #7	$34.95	7.218%	$37.4727	$37.47	$37.45	$37.50
7 purchase totals =	$657.93		$726.8980	$726.89	$726.90	$726.90