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	$229.55	3.616%	$237.8505	$237.85	$237.85	$237.90
Purchase #2	$173.48	9.501%	$189.9623	$189.96	$189.95	$190.00
Purchase #3	$66.61	8.351%	$72.1726	$72.17	$72.15	$72.20
Purchase #4	$173.34	5.296%	$182.5201	$182.52	$182.50	$182.50
Purchase #5	$82.34	12.843%	$92.9149	$92.91	$92.90	$92.90
Purchase #6	$172.50	11.209%	$191.8355	$191.84	$191.85	$191.80
Purchase #7	$54.45	3.396%	$56.2991	$56.30	$56.30	$56.30
7 purchase totals =	$952.27		$1,023.5550	$1,023.55	$1,023.50	$1,023.60