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	$182.77	11.442%	$203.6825	$203.68	$203.70	$203.70
Purchase #2	$190.80	7.168%	$204.4765	$204.48	$204.50	$204.50
Purchase #3	$189.35	11.782%	$211.6592	$211.66	$211.65	$211.70
Purchase #4	$100.34	10.753%	$111.1296	$111.13	$111.15	$111.10
Purchase #5	$91.88	7.190%	$98.4862	$98.49	$98.50	$98.50
Purchase #6	$31.32	10.847%	$34.7173	$34.72	$34.70	$34.70
Purchase #7	$173.90	6.865%	$185.8382	$185.84	$185.85	$185.80
7 purchase totals =	$960.36		$1,049.9895	$1,050.00	$1,050.05	$1,050.00