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	$116.61	5.534%	$123.0632	$123.06	$123.05	$123.10
Purchase #2	$168.75	3.342%	$174.3896	$174.39	$174.40	$174.40
Purchase #3	$72.91	3.506%	$75.4662	$75.47	$75.45	$75.50
Purchase #4	$128.33	13.759%	$145.9869	$145.99	$146.00	$146.00
Purchase #5	$99.96	8.466%	$108.4226	$108.42	$108.40	$108.40
Purchase #6	$221.52	7.320%	$237.7353	$237.74	$237.75	$237.70
Purchase #7	$191.75	12.821%	$216.3343	$216.33	$216.35	$216.30
7 purchase totals =	$999.83		$1,081.3981	$1,081.40	$1,081.40	$1,081.40