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	$176.57	12.179%	$198.0745	$198.07	$198.05	$198.10
Purchase #2	$194.64	11.655%	$217.3253	$217.33	$217.35	$217.30
Purchase #3	$88.54	12.147%	$99.295	$99.30	$99.30	$99.30
Purchase #4	$185.81	13.155%	$210.2533	$210.25	$210.25	$210.30
Purchase #5	$93.88	9.229%	$102.5442	$102.54	$102.55	$102.50
Purchase #6	$92.75	11.604%	$103.5127	$103.51	$103.50	$103.50
Purchase #7	$107.75	5.657%	$113.8454	$113.85	$113.85	$113.80
7 purchase totals =	$939.94		$1,044.8504	$1,044.85	$1,044.85	$1,044.80