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	$97.52	7.723%	$105.0515	$105.05	$105.05	$105.10
Purchase #2	$170.45	13.766%	$193.9141	$193.91	$193.90	$193.90
Purchase #3	$103.81	7.373%	$111.4639	$111.46	$111.45	$111.50
Purchase #4	$225.28	5.467%	$237.5961	$237.60	$237.60	$237.60
Purchase #5	$147.67	3.321%	$152.5741	$152.57	$152.55	$152.60
Purchase #6	$65.30	12.562%	$73.503	$73.50	$73.50	$73.50
Purchase #7	$140.60	5.533%	$148.3794	$148.38	$148.40	$148.40
7 purchase totals =	$950.63		$1,022.4821	$1,022.47	$1,022.45	$1,022.60