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	$55.43	10.773%	$61.4015	$61.40	$61.40	$61.40
Purchase #2	$190.68	3.218%	$196.8161	$196.82	$196.80	$196.80
Purchase #3	$241.36	13.505%	$273.9557	$273.96	$273.95	$274.00
Purchase #4	$102.74	8.686%	$111.664	$111.66	$111.65	$111.70
Purchase #5	$167.45	3.121%	$172.6761	$172.68	$172.70	$172.70
Purchase #6	$25.45	12.763%	$28.6982	$28.70	$28.70	$28.70
Purchase #7	$160.75	8.170%	$173.8833	$173.88	$173.90	$173.90
7 purchase totals =	$943.86		$1,019.0949	$1,019.10	$1,019.10	$1,019.20