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	$43.63	10.548%	$48.2321	$48.23	$48.25	$48.20
Purchase #2	$112.50	9.418%	$123.0953	$123.10	$123.10	$123.10
Purchase #3	$35.69	5.696%	$37.7229	$37.72	$37.70	$37.70
Purchase #4	$187.29	7.463%	$201.2675	$201.27	$201.25	$201.30
Purchase #5	$205.78	13.479%	$233.5171	$233.52	$233.50	$233.50
Purchase #6	$201.69	8.636%	$219.1079	$219.11	$219.10	$219.10
Purchase #7	$148.75	3.870%	$154.5066	$154.51	$154.50	$154.50
7 purchase totals =	$935.33		$1,017.4494	$1,017.46	$1,017.40	$1,017.40