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	$162.84	10.360%	$179.7102	$179.71	$179.70	$179.70
Purchase #2	$44.59	3.727%	$46.2519	$46.25	$46.25	$46.30
Purchase #3	$217.92	11.653%	$243.3142	$243.31	$243.30	$243.30
Purchase #4	$128.55	10.676%	$142.274	$142.27	$142.25	$142.30
Purchase #5	$129.29	12.504%	$145.4564	$145.46	$145.45	$145.50
Purchase #6	$109.27	12.551%	$122.9845	$122.98	$123.00	$123.00
Purchase #7	$190.80	10.356%	$210.5592	$210.56	$210.55	$210.60
7 purchase totals =	$983.26		$1,090.5504	$1,090.54	$1,090.50	$1,090.70