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	$207.36	3.239%	$214.0764	$214.08	$214.10	$214.10
Purchase #2	$138.43	4.851%	$145.1452	$145.15	$145.15	$145.10
Purchase #3	$72.49	4.727%	$75.9166	$75.92	$75.90	$75.90
Purchase #4	$91.76	10.668%	$101.549	$101.55	$101.55	$101.50
Purchase #5	$58.69	4.482%	$61.3205	$61.32	$61.30	$61.30
Purchase #6	$228.29	7.524%	$245.4665	$245.47	$245.45	$245.50
Purchase #7	$230.76	11.341%	$256.9305	$256.93	$256.95	$256.90
7 purchase totals =	$1,027.78		$1,100.4047	$1,100.42	$1,100.40	$1,100.30