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	$148.25	11.110%	$164.7206	$164.72	$164.70	$164.70
Purchase #2	$158.80	12.227%	$178.2165	$178.22	$178.20	$178.20
Purchase #3	$207.86	7.135%	$222.6908	$222.69	$222.70	$222.70
Purchase #4	$201.26	4.488%	$210.2925	$210.29	$210.30	$210.30
Purchase #5	$63.30	6.575%	$67.462	$67.46	$67.45	$67.50
Purchase #6	$154.59	3.520%	$160.0316	$160.03	$160.05	$160.00
Purchase #7	$131.51	10.461%	$145.2673	$145.27	$145.25	$145.30
7 purchase totals =	$1,065.57		$1,148.6813	$1,148.68	$1,148.65	$1,148.70