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	$148.76	5.433%	$156.8421	$156.84	$156.85	$156.80
Purchase #2	$241.83	10.360%	$266.8836	$266.88	$266.90	$266.90
Purchase #3	$86.58	10.574%	$95.735	$95.74	$95.75	$95.70
Purchase #4	$197.88	6.791%	$211.318	$211.32	$211.30	$211.30
Purchase #5	$42.89	6.567%	$45.7066	$45.71	$45.70	$45.70
Purchase #6	$126.37	8.276%	$136.8284	$136.83	$136.85	$136.80
Purchase #7	$102.68	8.559%	$111.4684	$111.47	$111.45	$111.50
7 purchase totals =	$946.99		$1,024.7821	$1,024.79	$1,024.80	$1,024.70