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	$198.56	3.260%	$205.0331	$205.03	$205.05	$205.00
Purchase #2	$100.29	4.788%	$105.0919	$105.09	$105.10	$105.10
Purchase #3	$96.29	13.545%	$109.3325	$109.33	$109.35	$109.30
Purchase #4	$52.41	8.854%	$57.0504	$57.05	$57.05	$57.10
Purchase #5	$62.56	6.131%	$66.3956	$66.40	$66.40	$66.40
Purchase #6	$239.53	9.277%	$261.7512	$261.75	$261.75	$261.80
Purchase #7	$233.54	7.239%	$250.446	$250.45	$250.45	$250.40
7 purchase totals =	$983.18		$1,055.1007	$1,055.10	$1,055.15	$1,055.10