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	$185.62	10.816%	$205.6967	$205.70	$205.70	$205.70
Purchase #2	$82.51	10.249%	$90.9664	$90.97	$90.95	$91.00
Purchase #3	$161.31	6.426%	$171.6758	$171.68	$171.70	$171.70
Purchase #4	$86.88	3.472%	$89.8965	$89.90	$89.90	$89.90
Purchase #5	$238.66	10.588%	$263.9293	$263.93	$263.95	$263.90
Purchase #6	$72.56	8.779%	$78.93	$78.93	$78.95	$78.90
Purchase #7	$149.64	9.138%	$163.3141	$163.31	$163.30	$163.30
7 purchase totals =	$977.18		$1,064.4088	$1,064.42	$1,064.45	$1,064.40