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	$198.69	4.463%	$207.5575	$207.56	$207.55	$207.60
Purchase #2	$39.67	4.508%	$41.4583	$41.46	$41.45	$41.50
Purchase #3	$247.77	7.825%	$267.158	$267.16	$267.15	$267.20
Purchase #4	$48.92	7.474%	$52.5763	$52.58	$52.60	$52.60
Purchase #5	$89.89	11.125%	$99.8903	$99.89	$99.90	$99.90
Purchase #6	$65.35	10.656%	$72.3137	$72.31	$72.30	$72.30
Purchase #7	$183.28	9.275%	$200.2792	$200.28	$200.30	$200.30
7 purchase totals =	$873.57		$941.2333	$941.24	$941.25	$941.40