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	$173.55	12.183%	$194.6936	$194.69	$194.70	$194.70
Purchase #2	$43.43	3.498%	$44.9492	$44.95	$44.95	$44.90
Purchase #3	$151.27	5.555%	$159.673	$159.67	$159.65	$159.70
Purchase #4	$160.63	3.666%	$166.5187	$166.52	$166.50	$166.50
Purchase #5	$48.67	9.831%	$53.4547	$53.45	$53.45	$53.50
Purchase #6	$223.33	10.296%	$246.3241	$246.32	$246.30	$246.30
Purchase #7	$127.74	10.850%	$141.5998	$141.60	$141.60	$141.60
7 purchase totals =	$928.62		$1,007.2131	$1,007.20	$1,007.15	$1,007.20