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	$201.83	11.616%	$225.2746	$225.27	$225.25	$225.30
Purchase #2	$53.98	7.203%	$57.8682	$57.87	$57.85	$57.90
Purchase #3	$174.30	12.862%	$196.7185	$196.72	$196.70	$196.70
Purchase #4	$160.73	4.120%	$167.3521	$167.35	$167.35	$167.40
Purchase #5	$60.71	7.135%	$65.0417	$65.04	$65.05	$65.00
Purchase #6	$52.65	3.719%	$54.6081	$54.61	$54.60	$54.60
Purchase #7	$237.85	7.362%	$255.3605	$255.36	$255.35	$255.40
7 purchase totals =	$942.05		$1,022.2237	$1,022.22	$1,022.15	$1,022.30