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	$208.85	4.345%	$217.9245	$217.92	$217.90	$217.90
Purchase #2	$64.69	10.213%	$71.2968	$71.30	$71.30	$71.30
Purchase #3	$27.61	4.282%	$28.7923	$28.79	$28.80	$28.80
Purchase #4	$174.72	9.474%	$191.273	$191.27	$191.25	$191.30
Purchase #5	$104.47	7.673%	$112.486	$112.49	$112.50	$112.50
Purchase #6	$204.83	3.119%	$211.2186	$211.22	$211.20	$211.20
Purchase #7	$64.32	5.159%	$67.6383	$67.64	$67.65	$67.60
7 purchase totals =	$849.49		$900.6295	$900.63	$900.60	$900.60