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	$167.84	8.156%	$181.529	$181.53	$181.55	$181.50
Purchase #2	$178.79	5.747%	$189.0651	$189.07	$189.05	$189.10
Purchase #3	$58.89	10.194%	$64.8932	$64.89	$64.90	$64.90
Purchase #4	$158.87	5.299%	$167.2885	$167.29	$167.30	$167.30
Purchase #5	$84.77	7.180%	$90.8565	$90.86	$90.85	$90.90
Purchase #6	$147.47	4.114%	$153.5369	$153.54	$153.55	$153.50
Purchase #7	$203.55	3.693%	$211.0671	$211.07	$211.05	$211.10
7 purchase totals =	$1,000.18		$1,058.2363	$1,058.25	$1,058.25	$1,058.30