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	$174.45	4.218%	$181.8083	$181.81	$181.80	$181.80
Purchase #2	$170.31	6.781%	$181.8587	$181.86	$181.85	$181.90
Purchase #3	$188.35	11.712%	$210.4096	$210.41	$210.40	$210.40
Purchase #4	$194.39	11.214%	$216.1889	$216.19	$216.20	$216.20
Purchase #5	$187.91	11.809%	$210.1003	$210.10	$210.10	$210.10
Purchase #6	$231.64	10.689%	$256.4	$256.40	$256.40	$256.40
Purchase #7	$177.33	10.735%	$196.3664	$196.37	$196.35	$196.40
7 purchase totals =	$1,324.38		$1,453.1322	$1,453.14	$1,453.10	$1,453.20