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	$144.31	4.649%	$151.019	$151.02	$151.00	$151.00
Purchase #2	$86.75	12.644%	$97.7187	$97.72	$97.70	$97.70
Purchase #3	$131.43	3.552%	$136.0984	$136.10	$136.10	$136.10
Purchase #4	$103.84	9.691%	$113.9031	$113.90	$113.90	$113.90
Purchase #5	$229.42	11.196%	$255.1059	$255.11	$255.10	$255.10
Purchase #6	$112.51	11.381%	$125.3148	$125.31	$125.30	$125.30
Purchase #7	$126.25	13.220%	$142.9403	$142.94	$142.95	$142.90
7 purchase totals =	$934.51		$1,022.1002	$1,022.10	$1,022.05	$1,022.00