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	$59.38	10.333%	$65.5157	$65.52	$65.50	$65.50
Purchase #2	$41.35	4.829%	$43.3468	$43.35	$43.35	$43.30
Purchase #3	$119.94	5.644%	$126.7094	$126.71	$126.70	$126.70
Purchase #4	$51.52	13.205%	$58.3232	$58.32	$58.30	$58.30
Purchase #5	$152.35	6.584%	$162.3807	$162.38	$162.40	$162.40
Purchase #6	$29.83	11.673%	$33.3121	$33.31	$33.30	$33.30
Purchase #7	$243.79	13.803%	$277.4403	$277.44	$277.45	$277.40
7 purchase totals =	$698.16		$767.0282	$767.03	$767.00	$766.90