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	$177.57	7.219%	$190.3888	$190.39	$190.40	$190.40
Purchase #2	$64.27	5.701%	$67.934	$67.93	$67.95	$67.90
Purchase #3	$243.42	7.250%	$261.068	$261.07	$261.05	$261.10
Purchase #4	$218.38	10.175%	$240.6002	$240.60	$240.60	$240.60
Purchase #5	$34.37	7.700%	$37.0165	$37.02	$37.00	$37.00
Purchase #6	$231.64	4.141%	$241.2322	$241.23	$241.25	$241.20
Purchase #7	$58.28	13.748%	$66.2923	$66.29	$66.30	$66.30
7 purchase totals =	$1,027.93		$1,104.5320	$1,104.53	$1,104.55	$1,104.50