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	$153.98	5.767%	$162.86	$162.86	$162.85	$162.90
Purchase #2	$230.50	11.328%	$256.611	$256.61	$256.60	$256.60
Purchase #3	$78.38	13.808%	$89.2027	$89.20	$89.20	$89.20
Purchase #4	$60.97	3.413%	$63.0509	$63.05	$63.05	$63.10
Purchase #5	$150.84	7.657%	$162.3898	$162.39	$162.40	$162.40
Purchase #6	$182.41	7.784%	$196.6088	$196.61	$196.60	$196.60
Purchase #7	$175.38	4.363%	$183.0318	$183.03	$183.05	$183.00
7 purchase totals =	$1,032.46		$1,113.7550	$1,113.75	$1,113.75	$1,113.80