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	$87.34	7.689%	$94.0556	$94.06	$94.05	$94.10
Purchase #2	$122.40	4.113%	$127.4343	$127.43	$127.45	$127.40
Purchase #3	$168.77	13.501%	$191.5556	$191.56	$191.55	$191.60
Purchase #4	$240.35	7.771%	$259.0276	$259.03	$259.05	$259.00
Purchase #5	$113.76	10.703%	$125.9357	$125.94	$125.95	$125.90
Purchase #6	$103.72	5.522%	$109.4474	$109.45	$109.45	$109.40
Purchase #7	$153.53	5.520%	$162.0049	$162.00	$162.00	$162.00
7 purchase totals =	$989.87		$1,069.4611	$1,069.47	$1,069.50	$1,069.40