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	$146.98	6.552%	$156.6101	$156.61	$156.60	$156.60
Purchase #2	$93.59	4.305%	$97.619	$97.62	$97.60	$97.60
Purchase #3	$47.53	5.839%	$50.3053	$50.31	$50.30	$50.30
Purchase #4	$196.38	4.450%	$205.1189	$205.12	$205.10	$205.10
Purchase #5	$174.37	13.111%	$197.2317	$197.23	$197.25	$197.20
Purchase #6	$155.60	10.414%	$171.8042	$171.80	$171.80	$171.80
Purchase #7	$150.55	10.139%	$165.8143	$165.81	$165.80	$165.80
7 purchase totals =	$965.00		$1,044.5035	$1,044.50	$1,044.45	$1,044.40