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	$145.54	5.563%	$153.6364	$153.64	$153.65	$153.60
Purchase #2	$100.68	5.251%	$105.9667	$105.97	$105.95	$106.00
Purchase #3	$95.36	4.119%	$99.2879	$99.29	$99.30	$99.30
Purchase #4	$249.33	10.312%	$275.0409	$275.04	$275.05	$275.00
Purchase #5	$73.46	12.324%	$82.5132	$82.51	$82.50	$82.50
Purchase #6	$190.78	3.789%	$198.0087	$198.01	$198.00	$198.00
Purchase #7	$186.42	5.736%	$197.1131	$197.11	$197.10	$197.10
7 purchase totals =	$1,041.57		$1,111.5669	$1,111.57	$1,111.55	$1,111.50