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	$43.96	10.257%	$48.469	$48.47	$48.45	$48.50
Purchase #2	$68.91	5.644%	$72.7993	$72.80	$72.80	$72.80
Purchase #3	$137.30	10.114%	$151.1865	$151.19	$151.20	$151.20
Purchase #4	$26.28	6.580%	$28.0092	$28.01	$28.00	$28.00
Purchase #5	$46.41	13.569%	$52.7074	$52.71	$52.70	$52.70
Purchase #6	$221.40	3.382%	$228.8877	$228.89	$228.90	$228.90
Purchase #7	$149.35	8.728%	$162.3853	$162.39	$162.40	$162.40
7 purchase totals =	$693.61		$744.4444	$744.46	$744.45	$744.50