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	$213.28	5.631%	$225.2898	$225.29	$225.30	$225.30
Purchase #2	$54.34	9.190%	$59.3338	$59.33	$59.35	$59.30
Purchase #3	$157.35	11.540%	$175.5082	$175.51	$175.50	$175.50
Purchase #4	$36.83	12.241%	$41.3384	$41.34	$41.35	$41.30
Purchase #5	$241.41	9.436%	$264.1894	$264.19	$264.20	$264.20
Purchase #6	$160.84	11.356%	$179.105	$179.11	$179.10	$179.10
Purchase #7	$103.87	7.303%	$111.4556	$111.46	$111.45	$111.50
7 purchase totals =	$967.92		$1,056.2202	$1,056.23	$1,056.25	$1,056.20