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	$59.63	5.548%	$62.9383	$62.94	$62.95	$62.90
Purchase #2	$16.73	4.656%	$17.5089	$17.51	$17.50	$17.50
Purchase #3	$179.53	5.831%	$189.9984	$190.00	$190.00	$190.00
Purchase #4	$33.76	10.192%	$37.2008	$37.20	$37.20	$37.20
Purchase #5	$239.58	10.109%	$263.7991	$263.80	$263.80	$263.80
Purchase #6	$134.39	13.500%	$152.5327	$152.53	$152.55	$152.50
Purchase #7	$105.35	12.502%	$118.5209	$118.52	$118.50	$118.50
7 purchase totals =	$768.97		$842.4991	$842.50	$842.50	$842.40