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	$188.63	3.234%	$194.7303	$194.73	$194.75	$194.70
Purchase #2	$126.54	3.435%	$130.8866	$130.89	$130.90	$130.90
Purchase #3	$44.38	8.786%	$48.2792	$48.28	$48.30	$48.30
Purchase #4	$118.96	4.665%	$124.5095	$124.51	$124.50	$124.50
Purchase #5	$244.59	5.309%	$257.5753	$257.58	$257.60	$257.60
Purchase #6	$158.67	5.811%	$167.8903	$167.89	$167.90	$167.90
Purchase #7	$142.62	3.108%	$147.0526	$147.05	$147.05	$147.10
7 purchase totals =	$1,024.39		$1,070.9238	$1,070.93	$1,071.00	$1,071.00