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	$181.59	9.164%	$198.2309	$198.23	$198.25	$198.20
Purchase #2	$29.81	13.787%	$33.9199	$33.92	$33.90	$33.90
Purchase #3	$199.42	10.193%	$219.7469	$219.75	$219.75	$219.70
Purchase #4	$42.85	7.417%	$46.0282	$46.03	$46.05	$46.00
Purchase #5	$56.94	13.339%	$64.5352	$64.54	$64.55	$64.50
Purchase #6	$228.30	6.296%	$242.6738	$242.67	$242.65	$242.70
Purchase #7	$230.55	5.790%	$243.8988	$243.90	$243.90	$243.90
7 purchase totals =	$969.46		$1,049.0337	$1,049.04	$1,049.05	$1,048.90