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	$155.81	4.542%	$162.8869	$162.89	$162.90	$162.90
Purchase #2	$65.94	11.671%	$73.6359	$73.64	$73.65	$73.60
Purchase #3	$141.40	4.644%	$147.9666	$147.97	$147.95	$148.00
Purchase #4	$127.71	6.541%	$136.0635	$136.06	$136.05	$136.10
Purchase #5	$73.67	12.336%	$82.7579	$82.76	$82.75	$82.80
Purchase #6	$91.89	3.765%	$95.3497	$95.35	$95.35	$95.30
Purchase #7	$49.78	7.194%	$53.3612	$53.36	$53.35	$53.40
7 purchase totals =	$706.20		$752.0217	$752.03	$752.00	$752.10