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	$226.69	3.822%	$235.3541	$235.35	$235.35	$235.40
Purchase #2	$115.80	13.672%	$131.6322	$131.63	$131.65	$131.60
Purchase #3	$191.80	7.574%	$206.3269	$206.33	$206.35	$206.30
Purchase #4	$63.34	3.111%	$65.3105	$65.31	$65.30	$65.30
Purchase #5	$87.47	13.668%	$99.4254	$99.43	$99.45	$99.40
Purchase #6	$244.95	4.842%	$256.8105	$256.81	$256.80	$256.80
Purchase #7	$153.57	9.277%	$167.8167	$167.82	$167.80	$167.80
7 purchase totals =	$1,083.62		$1,162.6763	$1,162.68	$1,162.70	$1,162.60