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	$162.64	4.207%	$169.4823	$169.48	$169.50	$169.50
Purchase #2	$212.38	5.169%	$223.3579	$223.36	$223.35	$223.40
Purchase #3	$10.36	4.403%	$10.8162	$10.82	$10.80	$10.80
Purchase #4	$153.98	7.866%	$166.0921	$166.09	$166.10	$166.10
Purchase #5	$229.35	4.227%	$239.0446	$239.04	$239.05	$239.00
Purchase #6	$179.72	9.211%	$196.274	$196.27	$196.25	$196.30
Purchase #7	$164.45	6.148%	$174.5604	$174.56	$174.55	$174.60
7 purchase totals =	$1,112.88		$1,179.6275	$1,179.62	$1,179.60	$1,179.70