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	$158.49	10.453%	$175.057	$175.06	$175.05	$175.10
Purchase #2	$41.80	9.537%	$45.7865	$45.79	$45.80	$45.80
Purchase #3	$31.51	4.800%	$33.0225	$33.02	$33.00	$33.00
Purchase #4	$208.57	10.514%	$230.499	$230.50	$230.50	$230.50
Purchase #5	$70.38	3.375%	$72.7553	$72.76	$72.75	$72.80
Purchase #6	$106.63	7.409%	$114.5302	$114.53	$114.55	$114.50
Purchase #7	$48.78	10.129%	$53.7209	$53.72	$53.70	$53.70
7 purchase totals =	$666.16		$725.3714	$725.38	$725.35	$725.40