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	$195.57	5.134%	$205.6106	$205.61	$205.60	$205.60
Purchase #2	$142.61	7.565%	$153.3984	$153.40	$153.40	$153.40
Purchase #3	$85.25	5.467%	$89.9106	$89.91	$89.90	$89.90
Purchase #4	$183.86	3.267%	$189.8667	$189.87	$189.85	$189.90
Purchase #5	$169.43	11.700%	$189.2533	$189.25	$189.25	$189.30
Purchase #6	$182.98	11.781%	$204.5369	$204.54	$204.55	$204.50
Purchase #7	$211.79	4.305%	$220.9076	$220.91	$220.90	$220.90
7 purchase totals =	$1,171.49		$1,253.4841	$1,253.49	$1,253.45	$1,253.50