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	$249.43	4.653%	$261.036	$261.04	$261.05	$261.00
Purchase #2	$200.38	4.752%	$209.9021	$209.90	$209.90	$209.90
Purchase #3	$114.64	13.834%	$130.4993	$130.50	$130.50	$130.50
Purchase #4	$33.47	3.460%	$34.6281	$34.63	$34.65	$34.60
Purchase #5	$207.51	8.552%	$225.2563	$225.26	$225.25	$225.30
Purchase #6	$216.62	7.576%	$233.0311	$233.03	$233.05	$233.00
Purchase #7	$52.55	13.492%	$59.64	$59.64	$59.65	$59.60
7 purchase totals =	$1,074.60		$1,153.9929	$1,154.00	$1,154.05	$1,153.90