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	$194.25	9.205%	$212.1307	$212.13	$212.15	$212.10
Purchase #2	$109.56	12.765%	$123.5453	$123.55	$123.55	$123.50
Purchase #3	$8.26	4.267%	$8.6125	$8.61	$8.60	$8.60
Purchase #4	$44.69	7.661%	$48.1137	$48.11	$48.10	$48.10
Purchase #5	$185.91	12.261%	$208.7044	$208.70	$208.70	$208.70
Purchase #6	$214.86	3.326%	$222.0062	$222.01	$222.00	$222.00
Purchase #7	$208.41	10.118%	$229.4969	$229.50	$229.50	$229.50
7 purchase totals =	$965.94		$1,052.6097	$1,052.61	$1,052.60	$1,052.50