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	$243.38	9.646%	$266.8564	$266.86	$266.85	$266.90
Purchase #2	$165.91	5.254%	$174.6269	$174.63	$174.65	$174.60
Purchase #3	$61.75	5.251%	$64.9925	$64.99	$65.00	$65.00
Purchase #4	$58.65	4.650%	$61.3772	$61.38	$61.40	$61.40
Purchase #5	$220.83	6.595%	$235.3937	$235.39	$235.40	$235.40
Purchase #6	$198.86	13.524%	$225.7538	$225.75	$225.75	$225.80
Purchase #7	$149.83	11.814%	$167.5309	$167.53	$167.55	$167.50
7 purchase totals =	$1,099.21		$1,196.5314	$1,196.53	$1,196.60	$1,196.60