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	$99.53	6.343%	$105.8432	$105.84	$105.85	$105.80
Purchase #2	$53.84	11.199%	$59.8695	$59.87	$59.85	$59.90
Purchase #3	$113.37	8.750%	$123.2899	$123.29	$123.30	$123.30
Purchase #4	$140.52	3.489%	$145.4227	$145.42	$145.40	$145.40
Purchase #5	$208.34	12.242%	$233.845	$233.85	$233.85	$233.80
Purchase #6	$244.97	6.760%	$261.53	$261.53	$261.55	$261.50
Purchase #7	$92.62	3.256%	$95.6357	$95.64	$95.65	$95.60
7 purchase totals =	$953.19		$1,025.4360	$1,025.44	$1,025.45	$1,025.30