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	$141.96	7.662%	$152.837	$152.84	$152.85	$152.80
Purchase #2	$103.69	7.111%	$111.0634	$111.06	$111.05	$111.10
Purchase #3	$49.43	10.135%	$54.4397	$54.44	$54.45	$54.40
Purchase #4	$216.46	4.290%	$225.7461	$225.75	$225.75	$225.70
Purchase #5	$207.26	5.559%	$218.7816	$218.78	$218.80	$218.80
Purchase #6	$121.98	5.355%	$128.512	$128.51	$128.50	$128.50
Purchase #7	$215.93	5.555%	$227.9249	$227.92	$227.90	$227.90
7 purchase totals =	$1,056.71		$1,119.3047	$1,119.30	$1,119.30	$1,119.20