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	$43.43	10.171%	$47.8473	$47.85	$47.85	$47.80
Purchase #2	$88.92	7.835%	$95.8869	$95.89	$95.90	$95.90
Purchase #3	$46.41	4.558%	$48.5254	$48.53	$48.55	$48.50
Purchase #4	$140.50	13.554%	$159.5434	$159.54	$159.55	$159.50
Purchase #5	$242.60	11.127%	$269.5941	$269.59	$269.60	$269.60
Purchase #6	$146.51	10.874%	$162.4415	$162.44	$162.45	$162.40
Purchase #7	$250.64	5.403%	$264.1821	$264.18	$264.20	$264.20
7 purchase totals =	$959.01		$1,048.0207	$1,048.02	$1,048.10	$1,047.90