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	$158.29	9.786%	$173.7803	$173.78	$173.80	$173.80
Purchase #2	$125.28	4.262%	$130.6194	$130.62	$130.60	$130.60
Purchase #3	$38.90	11.684%	$43.4451	$43.45	$43.45	$43.40
Purchase #4	$186.99	13.109%	$211.5025	$211.50	$211.50	$211.50
Purchase #5	$168.41	11.815%	$188.3076	$188.31	$188.30	$188.30
Purchase #6	$37.31	4.338%	$38.9285	$38.93	$38.95	$38.90
Purchase #7	$144.43	10.155%	$159.0969	$159.10	$159.10	$159.10
7 purchase totals =	$859.61		$945.6803	$945.69	$945.70	$945.60