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	$141.56	6.287%	$150.4599	$150.46	$150.45	$150.50
Purchase #2	$11.47	12.257%	$12.8759	$12.88	$12.90	$12.90
Purchase #3	$217.51	10.860%	$241.1316	$241.13	$241.15	$241.10
Purchase #4	$218.78	9.112%	$238.7152	$238.72	$238.70	$238.70
Purchase #5	$197.30	10.656%	$218.3243	$218.32	$218.30	$218.30
Purchase #6	$165.74	4.796%	$173.6889	$173.69	$173.70	$173.70
Purchase #7	$155.53	13.342%	$176.2808	$176.28	$176.30	$176.30
7 purchase totals =	$1,107.89		$1,211.4766	$1,211.48	$1,211.50	$1,211.50