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	$199.33	6.845%	$212.9741	$212.97	$212.95	$213.00
Purchase #2	$243.56	6.294%	$258.8897	$258.89	$258.90	$258.90
Purchase #3	$127.77	6.517%	$136.0968	$136.10	$136.10	$136.10
Purchase #4	$90.81	10.680%	$100.5085	$100.51	$100.50	$100.50
Purchase #5	$109.32	7.187%	$117.1768	$117.18	$117.20	$117.20
Purchase #6	$157.78	5.867%	$167.037	$167.04	$167.05	$167.00
Purchase #7	$162.71	3.103%	$167.7589	$167.76	$167.75	$167.80
7 purchase totals =	$1,091.28		$1,160.4418	$1,160.45	$1,160.45	$1,160.50