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	$40.76	13.152%	$46.1208	$46.12	$46.10	$46.10
Purchase #2	$149.32	12.872%	$168.5405	$168.54	$168.55	$168.50
Purchase #3	$85.58	8.392%	$92.7619	$92.76	$92.75	$92.80
Purchase #4	$51.81	3.771%	$53.7638	$53.76	$53.75	$53.80
Purchase #5	$211.55	13.815%	$240.7756	$240.78	$240.80	$240.80
Purchase #6	$147.26	10.574%	$162.8313	$162.83	$162.85	$162.80
Purchase #7	$111.30	5.524%	$117.4482	$117.45	$117.45	$117.40
7 purchase totals =	$797.58		$882.2421	$882.24	$882.25	$882.20