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	$146.93	4.371%	$153.3523	$153.35	$153.35	$153.40
Purchase #2	$210.75	10.684%	$233.2665	$233.27	$233.25	$233.30
Purchase #3	$241.75	4.794%	$253.3395	$253.34	$253.35	$253.30
Purchase #4	$207.33	10.716%	$229.5475	$229.55	$229.55	$229.50
Purchase #5	$71.88	7.533%	$77.2947	$77.29	$77.30	$77.30
Purchase #6	$145.96	11.173%	$162.2681	$162.27	$162.25	$162.30
Purchase #7	$33.50	6.793%	$35.7757	$35.78	$35.80	$35.80
7 purchase totals =	$1,058.10		$1,144.8443	$1,144.85	$1,144.85	$1,144.90