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	$72.86	4.549%	$76.1744	$76.17	$76.15	$76.20
Purchase #2	$40.88	10.297%	$45.0894	$45.09	$45.10	$45.10
Purchase #3	$107.27	10.823%	$118.8798	$118.88	$118.90	$118.90
Purchase #4	$193.91	9.610%	$212.5448	$212.54	$212.55	$212.50
Purchase #5	$30.57	8.285%	$33.1027	$33.10	$33.10	$33.10
Purchase #6	$116.50	12.814%	$131.4283	$131.43	$131.45	$131.40
Purchase #7	$102.35	6.276%	$108.7735	$108.77	$108.75	$108.80
7 purchase totals =	$664.34		$725.9929	$725.98	$726.00	$726.00