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	$195.32	5.753%	$206.5568	$206.56	$206.55	$206.60
Purchase #2	$89.68	6.582%	$95.5827	$95.58	$95.60	$95.60
Purchase #3	$105.45	3.194%	$108.8181	$108.82	$108.80	$108.80
Purchase #4	$164.91	9.458%	$180.5072	$180.51	$180.50	$180.50
Purchase #5	$41.52	10.747%	$45.9822	$45.98	$46.00	$46.00
Purchase #6	$168.97	11.170%	$187.8439	$187.84	$187.85	$187.80
Purchase #7	$113.35	12.581%	$127.6106	$127.61	$127.60	$127.60
7 purchase totals =	$879.20		$952.9015	$952.90	$952.90	$952.90