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	$245.47	7.117%	$262.9401	$262.94	$262.95	$262.90
Purchase #2	$247.43	3.389%	$255.8154	$255.82	$255.80	$255.80
Purchase #3	$51.47	8.551%	$55.8712	$55.87	$55.85	$55.90
Purchase #4	$164.30	9.733%	$180.2913	$180.29	$180.30	$180.30
Purchase #5	$40.51	3.370%	$41.8752	$41.88	$41.90	$41.90
Purchase #6	$204.38	4.296%	$213.1602	$213.16	$213.15	$213.20
Purchase #7	$154.52	9.468%	$169.15	$169.15	$169.15	$169.20
7 purchase totals =	$1,108.08		$1,179.1034	$1,179.11	$1,179.10	$1,179.20