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	$97.47	6.317%	$103.6272	$103.63	$103.65	$103.60
Purchase #2	$194.47	5.853%	$205.8523	$205.85	$205.85	$205.90
Purchase #3	$197.25	7.744%	$212.525	$212.53	$212.55	$212.50
Purchase #4	$95.61	12.609%	$107.6655	$107.67	$107.65	$107.70
Purchase #5	$209.89	10.103%	$231.0952	$231.10	$231.10	$231.10
Purchase #6	$160.81	11.624%	$179.5026	$179.50	$179.50	$179.50
Purchase #7	$64.96	9.393%	$71.0617	$71.06	$71.05	$71.10
7 purchase totals =	$1,020.46		$1,111.3295	$1,111.34	$1,111.35	$1,111.40