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	$106.73	6.824%	$114.0133	$114.01	$114.00	$114.00
Purchase #2	$59.38	4.664%	$62.1495	$62.15	$62.15	$62.10
Purchase #3	$56.58	4.505%	$59.1289	$59.13	$59.15	$59.10
Purchase #4	$58.84	10.730%	$65.1535	$65.15	$65.15	$65.20
Purchase #5	$177.68	5.442%	$187.3493	$187.35	$187.35	$187.30
Purchase #6	$222.28	10.114%	$244.7614	$244.76	$244.75	$244.80
Purchase #7	$196.69	8.439%	$213.2887	$213.29	$213.30	$213.30
7 purchase totals =	$878.18		$945.8446	$945.84	$945.85	$945.80