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	$133.40	5.729%	$141.0425	$141.04	$141.05	$141.00
Purchase #2	$48.43	11.511%	$54.0048	$54.00	$54.00	$54.00
Purchase #3	$68.45	7.237%	$73.4037	$73.40	$73.40	$73.40
Purchase #4	$206.56	6.584%	$220.1599	$220.16	$220.15	$220.20
Purchase #5	$241.56	9.560%	$264.6531	$264.65	$264.65	$264.70
Purchase #6	$73.51	6.860%	$78.5528	$78.55	$78.55	$78.60
Purchase #7	$173.51	4.649%	$181.5765	$181.58	$181.60	$181.60
7 purchase totals =	$945.42		$1,013.3933	$1,013.38	$1,013.40	$1,013.50