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	$167.50	6.604%	$178.5617	$178.56	$178.55	$178.60
Purchase #2	$153.97	8.850%	$167.5963	$167.60	$167.60	$167.60
Purchase #3	$150.69	5.268%	$158.6283	$158.63	$158.65	$158.60
Purchase #4	$48.57	13.494%	$55.124	$55.12	$55.10	$55.10
Purchase #5	$195.83	6.446%	$208.4532	$208.45	$208.45	$208.50
Purchase #6	$60.83	10.227%	$67.0511	$67.05	$67.05	$67.10
Purchase #7	$248.32	3.417%	$256.8051	$256.81	$256.80	$256.80
7 purchase totals =	$1,025.71		$1,092.2197	$1,092.22	$1,092.20	$1,092.30