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	$46.76	3.528%	$48.4097	$48.41	$48.40	$48.40
Purchase #2	$210.47	10.339%	$232.2305	$232.23	$232.25	$232.20
Purchase #3	$89.72	13.376%	$101.7209	$101.72	$101.70	$101.70
Purchase #4	$124.46	3.270%	$128.5298	$128.53	$128.55	$128.50
Purchase #5	$147.65	10.140%	$162.6217	$162.62	$162.60	$162.60
Purchase #6	$241.77	13.353%	$274.0535	$274.05	$274.05	$274.10
Purchase #7	$56.28	11.113%	$62.5344	$62.53	$62.55	$62.50
7 purchase totals =	$917.11		$1,010.1005	$1,010.09	$1,010.10	$1,010.00