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	$191.71	9.753%	$210.4075	$210.41	$210.40	$210.40
Purchase #2	$142.56	11.849%	$159.4519	$159.45	$159.45	$159.50
Purchase #3	$217.38	5.462%	$229.2533	$229.25	$229.25	$229.30
Purchase #4	$59.86	13.665%	$68.0399	$68.04	$68.05	$68.00
Purchase #5	$235.41	6.318%	$250.2832	$250.28	$250.30	$250.30
Purchase #6	$189.81	3.441%	$196.3414	$196.34	$196.35	$196.30
Purchase #7	$58.34	7.288%	$62.5918	$62.59	$62.60	$62.60
7 purchase totals =	$1,095.07		$1,176.3690	$1,176.36	$1,176.40	$1,176.40