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	$142.94	9.103%	$155.9518	$155.95	$155.95	$156.00
Purchase #2	$170.71	5.343%	$179.831	$179.83	$179.85	$179.80
Purchase #3	$234.59	3.499%	$242.7983	$242.80	$242.80	$242.80
Purchase #4	$106.99	3.547%	$110.7849	$110.78	$110.80	$110.80
Purchase #5	$48.55	12.658%	$54.6955	$54.70	$54.70	$54.70
Purchase #6	$156.45	9.823%	$171.8181	$171.82	$171.80	$171.80
Purchase #7	$118.53	11.589%	$132.2664	$132.27	$132.25	$132.30
7 purchase totals =	$978.76		$1,048.1460	$1,048.15	$1,048.15	$1,048.20