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	$191.96	4.246%	$200.1106	$200.11	$200.10	$200.10
Purchase #2	$205.68	3.333%	$212.5353	$212.54	$212.55	$212.50
Purchase #3	$215.62	3.686%	$223.5678	$223.57	$223.55	$223.60
Purchase #4	$65.47	9.364%	$71.6006	$71.60	$71.60	$71.60
Purchase #5	$64.82	11.144%	$72.0435	$72.04	$72.05	$72.00
Purchase #6	$122.31	12.521%	$137.6244	$137.62	$137.60	$137.60
Purchase #7	$184.55	6.175%	$195.946	$195.95	$195.95	$195.90
7 purchase totals =	$1,050.41		$1,113.4282	$1,113.43	$1,113.40	$1,113.30