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	$114.82	13.496%	$130.3161	$130.32	$130.30	$130.30
Purchase #2	$115.76	9.143%	$126.3439	$126.34	$126.35	$126.30
Purchase #3	$169.34	9.542%	$185.4984	$185.50	$185.50	$185.50
Purchase #4	$214.60	4.608%	$224.4888	$224.49	$224.50	$224.50
Purchase #5	$108.72	11.541%	$121.2674	$121.27	$121.25	$121.30
Purchase #6	$213.54	11.680%	$238.4815	$238.48	$238.50	$238.50
Purchase #7	$85.56	13.803%	$97.3698	$97.37	$97.35	$97.40
7 purchase totals =	$1,022.34		$1,123.7659	$1,123.77	$1,123.75	$1,123.80