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	$224.56	8.673%	$244.0361	$244.04	$244.05	$244.00
Purchase #2	$48.45	10.323%	$53.4515	$53.45	$53.45	$53.50
Purchase #3	$53.58	10.521%	$59.2172	$59.22	$59.20	$59.20
Purchase #4	$176.38	3.328%	$182.2499	$182.25	$182.25	$182.20
Purchase #5	$145.31	13.342%	$164.6973	$164.70	$164.70	$164.70
Purchase #6	$103.57	9.806%	$113.7261	$113.73	$113.75	$113.70
Purchase #7	$176.25	7.741%	$189.8935	$189.89	$189.90	$189.90
7 purchase totals =	$928.10		$1,007.2716	$1,007.28	$1,007.30	$1,007.20