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	$54.86	12.308%	$61.6122	$61.61	$61.60	$61.60
Purchase #2	$102.86	7.405%	$110.4768	$110.48	$110.50	$110.50
Purchase #3	$133.80	6.441%	$142.4181	$142.42	$142.40	$142.40
Purchase #4	$179.80	11.776%	$200.9732	$200.97	$200.95	$201.00
Purchase #5	$122.83	6.234%	$130.4872	$130.49	$130.50	$130.50
Purchase #6	$105.28	10.871%	$116.725	$116.73	$116.75	$116.70
Purchase #7	$221.68	9.621%	$243.0078	$243.01	$243.00	$243.00
7 purchase totals =	$921.11		$1,005.7003	$1,005.71	$1,005.70	$1,005.70