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	$74.69	4.463%	$78.0234	$78.02	$78.00	$78.00
Purchase #2	$136.64	4.210%	$142.3925	$142.39	$142.40	$142.40
Purchase #3	$47.62	13.116%	$53.8658	$53.87	$53.85	$53.90
Purchase #4	$159.80	5.289%	$168.2518	$168.25	$168.25	$168.30
Purchase #5	$216.93	8.815%	$236.0524	$236.05	$236.05	$236.10
Purchase #6	$232.57	13.255%	$263.3972	$263.40	$263.40	$263.40
Purchase #7	$153.61	7.654%	$165.3673	$165.37	$165.35	$165.40
7 purchase totals =	$1,021.86		$1,107.3504	$1,107.35	$1,107.30	$1,107.50