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	$206.65	9.247%	$225.7589	$225.76	$225.75	$225.80
Purchase #2	$236.33	13.595%	$268.4591	$268.46	$268.45	$268.50
Purchase #3	$146.62	4.348%	$152.995	$153.00	$153.00	$153.00
Purchase #4	$78.54	13.764%	$89.3502	$89.35	$89.35	$89.40
Purchase #5	$22.89	7.340%	$24.5701	$24.57	$24.55	$24.60
Purchase #6	$188.73	7.267%	$202.445	$202.45	$202.45	$202.40
Purchase #7	$217.53	7.129%	$233.0377	$233.04	$233.05	$233.00
7 purchase totals =	$1,097.29		$1,196.6160	$1,196.63	$1,196.60	$1,196.70