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	$171.47	13.637%	$194.8534	$194.85	$194.85	$194.90
Purchase #2	$29.62	10.135%	$32.622	$32.62	$32.60	$32.60
Purchase #3	$38.65	7.819%	$41.672	$41.67	$41.65	$41.70
Purchase #4	$34.43	9.677%	$37.7618	$37.76	$37.75	$37.80
Purchase #5	$243.90	11.760%	$272.5826	$272.58	$272.60	$272.60
Purchase #6	$231.92	6.592%	$247.2082	$247.21	$247.20	$247.20
Purchase #7	$173.45	13.177%	$196.3055	$196.31	$196.30	$196.30
7 purchase totals =	$923.44		$1,023.0055	$1,023.00	$1,022.95	$1,023.10