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	$167.72	10.639%	$185.5637	$185.56	$185.55	$185.60
Purchase #2	$112.81	9.793%	$123.8575	$123.86	$123.85	$123.90
Purchase #3	$192.45	7.749%	$207.363	$207.36	$207.35	$207.40
Purchase #4	$143.96	11.399%	$160.37	$160.37	$160.35	$160.40
Purchase #5	$65.58	12.253%	$73.6155	$73.62	$73.60	$73.60
Purchase #6	$186.46	3.408%	$192.8146	$192.81	$192.80	$192.80
Purchase #7	$78.38	5.196%	$82.4526	$82.45	$82.45	$82.50
7 purchase totals =	$947.36		$1,026.0369	$1,026.03	$1,025.95	$1,026.20