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	$82.96	3.848%	$86.1523	$86.15	$86.15	$86.20
Purchase #2	$26.65	5.166%	$28.0267	$28.03	$28.05	$28.00
Purchase #3	$83.47	7.689%	$89.888	$89.89	$89.90	$89.90
Purchase #4	$53.64	7.186%	$57.4946	$57.49	$57.50	$57.50
Purchase #5	$111.38	13.201%	$126.0833	$126.08	$126.10	$126.10
Purchase #6	$56.36	5.348%	$59.3741	$59.37	$59.35	$59.40
Purchase #7	$219.56	11.607%	$245.0443	$245.04	$245.05	$245.00
7 purchase totals =	$634.02		$692.0633	$692.05	$692.10	$692.10