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	$50.85	7.514%	$54.6709	$54.67	$54.65	$54.70
Purchase #2	$50.31	8.487%	$54.5798	$54.58	$54.60	$54.60
Purchase #3	$236.42	3.766%	$245.3236	$245.32	$245.30	$245.30
Purchase #4	$162.52	12.380%	$182.64	$182.64	$182.65	$182.60
Purchase #5	$44.59	13.784%	$50.7363	$50.74	$50.75	$50.70
Purchase #6	$53.76	3.231%	$55.497	$55.50	$55.50	$55.50
Purchase #7	$53.71	10.543%	$59.3726	$59.37	$59.35	$59.40
7 purchase totals =	$652.16		$702.8202	$702.82	$702.80	$702.80