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	$185.76	5.585%	$196.1347	$196.13	$196.15	$196.10
Purchase #2	$246.62	12.258%	$276.8507	$276.85	$276.85	$276.90
Purchase #3	$30.92	4.541%	$32.3241	$32.32	$32.30	$32.30
Purchase #4	$103.43	9.706%	$113.4689	$113.47	$113.45	$113.50
Purchase #5	$55.53	6.613%	$59.2022	$59.20	$59.20	$59.20
Purchase #6	$14.57	13.560%	$16.5457	$16.55	$16.55	$16.50
Purchase #7	$37.54	4.343%	$39.1704	$39.17	$39.15	$39.20
7 purchase totals =	$674.37		$733.6967	$733.69	$733.65	$733.70