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	$89.28	6.359%	$94.9573	$94.96	$94.95	$95.00
Purchase #2	$64.43	9.222%	$70.3717	$70.37	$70.35	$70.40
Purchase #3	$56.89	7.742%	$61.2944	$61.29	$61.30	$61.30
Purchase #4	$157.27	4.789%	$164.8017	$164.80	$164.80	$164.80
Purchase #5	$32.61	12.252%	$36.6054	$36.61	$36.60	$36.60
Purchase #6	$58.52	11.418%	$65.2018	$65.20	$65.20	$65.20
Purchase #7	$118.80	9.620%	$130.2286	$130.23	$130.25	$130.20
7 purchase totals =	$577.80		$623.4609	$623.46	$623.45	$623.50