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	$99.34	5.759%	$105.061	$105.06	$105.05	$105.10
Purchase #2	$190.61	4.700%	$199.5687	$199.57	$199.55	$199.60
Purchase #3	$77.35	11.776%	$86.4587	$86.46	$86.45	$86.50
Purchase #4	$187.94	11.789%	$210.0962	$210.10	$210.10	$210.10
Purchase #5	$55.52	13.621%	$63.0824	$63.08	$63.10	$63.10
Purchase #6	$162.62	3.117%	$167.6889	$167.69	$167.70	$167.70
Purchase #7	$167.54	3.383%	$173.2079	$173.21	$173.20	$173.20
7 purchase totals =	$940.92		$1,005.1638	$1,005.17	$1,005.15	$1,005.30