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	$96.38	11.689%	$107.6459	$107.65	$107.65	$107.60
Purchase #2	$61.74	5.725%	$65.2746	$65.27	$65.25	$65.30
Purchase #3	$166.84	12.482%	$187.665	$187.67	$187.65	$187.70
Purchase #4	$166.59	11.324%	$185.4547	$185.45	$185.45	$185.50
Purchase #5	$130.98	10.228%	$144.3766	$144.38	$144.40	$144.40
Purchase #6	$130.41	10.627%	$144.2687	$144.27	$144.25	$144.30
Purchase #7	$228.41	13.521%	$259.2933	$259.29	$259.30	$259.30
7 purchase totals =	$981.35		$1,093.9788	$1,093.98	$1,093.95	$1,094.10