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	$191.50	8.636%	$208.0379	$208.04	$208.05	$208.00
Purchase #2	$153.36	8.322%	$166.1226	$166.12	$166.10	$166.10
Purchase #3	$50.33	4.199%	$52.4434	$52.44	$52.45	$52.40
Purchase #4	$127.39	11.738%	$142.343	$142.34	$142.35	$142.30
Purchase #5	$90.26	10.321%	$99.5757	$99.58	$99.60	$99.60
Purchase #6	$157.75	13.206%	$178.5825	$178.58	$178.60	$178.60
Purchase #7	$239.30	10.307%	$263.9647	$263.96	$263.95	$264.00
7 purchase totals =	$1,009.89		$1,111.0698	$1,111.06	$1,111.10	$1,111.00