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	$57.68	7.609%	$62.0689	$62.07	$62.05	$62.10
Purchase #2	$185.46	5.532%	$195.7196	$195.72	$195.70	$195.70
Purchase #3	$225.95	13.218%	$255.8161	$255.82	$255.80	$255.80
Purchase #4	$172.35	6.123%	$182.903	$182.90	$182.90	$182.90
Purchase #5	$156.86	6.569%	$167.1641	$167.16	$167.15	$167.20
Purchase #6	$155.89	12.507%	$175.3872	$175.39	$175.40	$175.40
Purchase #7	$163.81	5.124%	$172.2036	$172.20	$172.20	$172.20
7 purchase totals =	$1,118.00		$1,211.2625	$1,211.26	$1,211.20	$1,211.30