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	$45.28	3.634%	$46.9255	$46.93	$46.95	$46.90
Purchase #2	$231.64	13.380%	$262.6334	$262.63	$262.65	$262.60
Purchase #3	$70.69	3.118%	$72.8941	$72.89	$72.90	$72.90
Purchase #4	$203.76	3.198%	$210.2762	$210.28	$210.30	$210.30
Purchase #5	$241.79	13.179%	$273.6555	$273.66	$273.65	$273.70
Purchase #6	$43.87	12.247%	$49.2428	$49.24	$49.25	$49.20
Purchase #7	$139.39	4.528%	$145.7016	$145.70	$145.70	$145.70
7 purchase totals =	$976.42		$1,061.3291	$1,061.33	$1,061.40	$1,061.30