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	$62.29	13.711%	$70.8306	$70.83	$70.85	$70.80
Purchase #2	$105.63	5.626%	$111.5727	$111.57	$111.55	$111.60
Purchase #3	$182.77	5.118%	$192.1242	$192.12	$192.10	$192.10
Purchase #4	$143.55	7.140%	$153.7995	$153.80	$153.80	$153.80
Purchase #5	$33.54	13.256%	$37.9861	$37.99	$38.00	$38.00
Purchase #6	$188.83	5.142%	$198.5396	$198.54	$198.55	$198.50
Purchase #7	$224.67	12.299%	$252.3022	$252.30	$252.30	$252.30
7 purchase totals =	$941.28		$1,017.1549	$1,017.15	$1,017.15	$1,017.10