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	$237.75	11.135%	$264.2235	$264.22	$264.20	$264.20
Purchase #2	$48.50	7.152%	$51.9687	$51.97	$51.95	$52.00
Purchase #3	$66.59	9.396%	$72.8468	$72.85	$72.85	$72.80
Purchase #4	$198.96	4.560%	$208.0326	$208.03	$208.05	$208.00
Purchase #5	$151.83	9.784%	$166.685	$166.69	$166.70	$166.70
Purchase #6	$208.31	4.156%	$216.9674	$216.97	$216.95	$217.00
Purchase #7	$233.94	12.651%	$263.5357	$263.54	$263.55	$263.50
7 purchase totals =	$1,145.88		$1,244.2597	$1,244.27	$1,244.25	$1,244.20