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	$195.46	4.576%	$204.4042	$204.40	$204.40	$204.40
Purchase #2	$182.76	7.520%	$196.5036	$196.50	$196.50	$196.50
Purchase #3	$69.43	5.267%	$73.0869	$73.09	$73.10	$73.10
Purchase #4	$90.43	12.794%	$101.9996	$102.00	$102.00	$102.00
Purchase #5	$196.39	12.692%	$221.3158	$221.32	$221.30	$221.30
Purchase #6	$188.65	13.376%	$213.8838	$213.88	$213.90	$213.90
Purchase #7	$168.65	6.314%	$179.2986	$179.30	$179.30	$179.30
7 purchase totals =	$1,091.77		$1,190.4925	$1,190.49	$1,190.50	$1,190.50