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	$77.78	5.500%	$82.0579	$82.06	$82.05	$82.10
Purchase #2	$209.54	4.633%	$219.248	$219.25	$219.25	$219.20
Purchase #3	$70.54	10.383%	$77.8642	$77.86	$77.85	$77.90
Purchase #4	$8.39	6.404%	$8.9273	$8.93	$8.95	$8.90
Purchase #5	$94.96	3.601%	$98.3795	$98.38	$98.40	$98.40
Purchase #6	$227.58	6.237%	$241.7742	$241.77	$241.75	$241.80
Purchase #7	$212.43	4.439%	$221.8598	$221.86	$221.85	$221.90
7 purchase totals =	$901.22		$950.1109	$950.11	$950.10	$950.20