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	$118.74	10.276%	$130.9417	$130.94	$130.95	$130.90
Purchase #2	$61.63	5.107%	$64.7774	$64.78	$64.80	$64.80
Purchase #3	$250.82	8.300%	$271.6381	$271.64	$271.65	$271.60
Purchase #4	$38.39	13.844%	$43.7047	$43.70	$43.70	$43.70
Purchase #5	$108.48	9.368%	$118.6424	$118.64	$118.65	$118.60
Purchase #6	$250.33	7.745%	$269.7181	$269.72	$269.70	$269.70
Purchase #7	$148.33	10.651%	$164.1286	$164.13	$164.15	$164.10
7 purchase totals =	$976.72		$1,063.5510	$1,063.55	$1,063.60	$1,063.40