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	$141.34	10.533%	$156.2273	$156.23	$156.25	$156.20
Purchase #2	$151.62	11.196%	$168.5954	$168.60	$168.60	$168.60
Purchase #3	$38.96	4.308%	$40.6384	$40.64	$40.65	$40.60
Purchase #4	$99.70	3.796%	$103.4846	$103.48	$103.50	$103.50
Purchase #5	$212.55	8.808%	$231.2714	$231.27	$231.25	$231.30
Purchase #6	$144.56	10.156%	$159.2415	$159.24	$159.25	$159.20
Purchase #7	$186.49	4.191%	$194.3058	$194.31	$194.30	$194.30
7 purchase totals =	$975.22		$1,053.7644	$1,053.77	$1,053.80	$1,053.70