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	$230.49	8.770%	$250.704	$250.70	$250.70	$250.70
Purchase #2	$55.63	6.607%	$59.3055	$59.31	$59.30	$59.30
Purchase #3	$9.55	10.711%	$10.5729	$10.57	$10.55	$10.60
Purchase #4	$137.88	11.409%	$153.6107	$153.61	$153.60	$153.60
Purchase #5	$156.37	5.541%	$165.0345	$165.03	$165.05	$165.00
Purchase #6	$217.67	9.107%	$237.4932	$237.49	$237.50	$237.50
Purchase #7	$159.95	7.260%	$171.5624	$171.56	$171.55	$171.60
7 purchase totals =	$967.54		$1,048.2832	$1,048.27	$1,048.25	$1,048.30