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	$174.65	4.365%	$182.2735	$182.27	$182.25	$182.30
Purchase #2	$29.47	3.771%	$30.5813	$30.58	$30.60	$30.60
Purchase #3	$184.60	5.416%	$194.5979	$194.60	$194.60	$194.60
Purchase #4	$162.43	8.496%	$176.2301	$176.23	$176.25	$176.20
Purchase #5	$113.84	12.317%	$127.8617	$127.86	$127.85	$127.90
Purchase #6	$131.25	12.576%	$147.756	$147.76	$147.75	$147.80
Purchase #7	$189.61	3.613%	$196.4606	$196.46	$196.45	$196.50
7 purchase totals =	$985.85		$1,055.7611	$1,055.76	$1,055.75	$1,055.90