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	$24.58	3.515%	$25.444	$25.44	$25.45	$25.40
Purchase #2	$215.97	3.712%	$223.9868	$223.99	$224.00	$224.00
Purchase #3	$39.65	4.588%	$41.4691	$41.47	$41.45	$41.50
Purchase #4	$160.73	7.588%	$172.9262	$172.93	$172.95	$172.90
Purchase #5	$168.54	10.227%	$185.7766	$185.78	$185.80	$185.80
Purchase #6	$198.88	6.152%	$211.1151	$211.12	$211.10	$211.10
Purchase #7	$192.42	4.229%	$200.5574	$200.56	$200.55	$200.60
7 purchase totals =	$1,000.77		$1,061.2752	$1,061.29	$1,061.30	$1,061.30