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	$76.53	8.148%	$82.7657	$82.77	$82.75	$82.80
Purchase #2	$181.86	3.140%	$187.5704	$187.57	$187.55	$187.60
Purchase #3	$5.31	6.381%	$5.6488	$5.65	$5.65	$5.60
Purchase #4	$164.70	13.250%	$186.5228	$186.52	$186.50	$186.50
Purchase #5	$44.47	9.271%	$48.5928	$48.59	$48.60	$48.60
Purchase #6	$151.71	3.124%	$156.4494	$156.45	$156.45	$156.40
Purchase #7	$79.79	6.701%	$85.1367	$85.14	$85.15	$85.10
7 purchase totals =	$704.37		$752.6866	$752.69	$752.65	$752.60