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	$144.85	5.331%	$152.572	$152.57	$152.55	$152.60
Purchase #2	$153.39	6.846%	$163.8911	$163.89	$163.90	$163.90
Purchase #3	$145.44	3.654%	$150.7544	$150.75	$150.75	$150.80
Purchase #4	$164.69	13.711%	$187.2706	$187.27	$187.25	$187.30
Purchase #5	$104.31	4.693%	$109.2053	$109.21	$109.20	$109.20
Purchase #6	$108.86	13.234%	$123.2665	$123.27	$123.25	$123.30
Purchase #7	$248.77	11.188%	$276.6024	$276.60	$276.60	$276.60
7 purchase totals =	$1,070.31		$1,163.5623	$1,163.56	$1,163.50	$1,163.70