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	$181.68	8.194%	$196.5669	$196.57	$196.55	$196.60
Purchase #2	$129.54	11.567%	$144.5239	$144.52	$144.50	$144.50
Purchase #3	$169.31	6.332%	$180.0307	$180.03	$180.05	$180.00
Purchase #4	$192.80	6.552%	$205.4323	$205.43	$205.45	$205.40
Purchase #5	$163.38	6.869%	$174.6026	$174.60	$174.60	$174.60
Purchase #6	$98.30	11.657%	$109.7588	$109.76	$109.75	$109.80
Purchase #7	$79.25	5.426%	$83.5501	$83.55	$83.55	$83.60
7 purchase totals =	$1,014.26		$1,094.4653	$1,094.46	$1,094.45	$1,094.50