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	$90.80	3.786%	$94.2377	$94.24	$94.25	$94.20
Purchase #2	$10.37	11.330%	$11.5449	$11.54	$11.55	$11.50
Purchase #3	$66.45	7.612%	$71.5082	$71.51	$71.50	$71.50
Purchase #4	$250.52	3.545%	$259.4009	$259.40	$259.40	$259.40
Purchase #5	$213.31	12.161%	$239.2506	$239.25	$239.25	$239.30
Purchase #6	$162.46	3.230%	$167.7075	$167.71	$167.70	$167.70
Purchase #7	$211.44	12.451%	$237.7664	$237.77	$237.75	$237.80
7 purchase totals =	$1,005.35		$1,081.4162	$1,081.42	$1,081.40	$1,081.40