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	$107.96	4.798%	$113.1399	$113.14	$113.15	$113.10
Purchase #2	$248.34	6.554%	$264.6162	$264.62	$264.60	$264.60
Purchase #3	$109.69	6.224%	$116.5171	$116.52	$116.50	$116.50
Purchase #4	$211.94	7.500%	$227.8355	$227.84	$227.85	$227.80
Purchase #5	$84.80	5.810%	$89.7269	$89.73	$89.75	$89.70
Purchase #6	$142.83	5.463%	$150.6328	$150.63	$150.65	$150.60
Purchase #7	$75.28	8.695%	$81.8256	$81.83	$81.85	$81.80
7 purchase totals =	$980.84		$1,044.2940	$1,044.31	$1,044.35	$1,044.10