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	$213.41	4.404%	$222.8086	$222.81	$222.80	$222.80
Purchase #2	$65.28	12.298%	$73.3081	$73.31	$73.30	$73.30
Purchase #3	$189.47	4.308%	$197.6324	$197.63	$197.65	$197.60
Purchase #4	$193.33	11.432%	$215.4315	$215.43	$215.45	$215.40
Purchase #5	$9.33	4.451%	$9.7453	$9.75	$9.75	$9.70
Purchase #6	$51.72	4.110%	$53.8457	$53.85	$53.85	$53.80
Purchase #7	$56.69	5.646%	$59.8907	$59.89	$59.90	$59.90
7 purchase totals =	$779.23		$832.6623	$832.67	$832.70	$832.50