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	$187.31	13.168%	$211.975	$211.98	$212.00	$212.00
Purchase #2	$96.94	3.436%	$100.2709	$100.27	$100.25	$100.30
Purchase #3	$235.82	3.161%	$243.2743	$243.27	$243.25	$243.30
Purchase #4	$44.70	4.436%	$46.6829	$46.68	$46.70	$46.70
Purchase #5	$245.76	11.846%	$274.8727	$274.87	$274.85	$274.90
Purchase #6	$34.64	5.663%	$36.6017	$36.60	$36.60	$36.60
Purchase #7	$96.70	7.137%	$103.6015	$103.60	$103.60	$103.60
7 purchase totals =	$941.87		$1,017.2790	$1,017.27	$1,017.25	$1,017.40