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	$211.88	5.621%	$223.7898	$223.79	$223.80	$223.80
Purchase #2	$93.92	4.435%	$98.0854	$98.09	$98.10	$98.10
Purchase #3	$71.49	9.156%	$78.0356	$78.04	$78.05	$78.00
Purchase #4	$34.56	5.460%	$36.447	$36.45	$36.45	$36.40
Purchase #5	$164.35	11.250%	$182.8394	$182.84	$182.85	$182.80
Purchase #6	$164.27	5.246%	$172.8876	$172.89	$172.90	$172.90
Purchase #7	$154.98	9.773%	$170.1262	$170.13	$170.15	$170.10
7 purchase totals =	$895.45		$962.2110	$962.23	$962.30	$962.10