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	$112.65	10.659%	$124.6574	$124.66	$124.65	$124.70
Purchase #2	$35.34	10.484%	$39.045	$39.05	$39.05	$39.00
Purchase #3	$66.55	8.278%	$72.059	$72.06	$72.05	$72.10
Purchase #4	$243.51	13.355%	$276.0308	$276.03	$276.05	$276.00
Purchase #5	$184.62	6.467%	$196.5594	$196.56	$196.55	$196.60
Purchase #6	$242.93	10.542%	$268.5397	$268.54	$268.55	$268.50
Purchase #7	$180.86	4.299%	$188.6352	$188.64	$188.65	$188.60
7 purchase totals =	$1,066.46		$1,165.5265	$1,165.54	$1,165.55	$1,165.50