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	$155.30	3.708%	$161.0585	$161.06	$161.05	$161.10
Purchase #2	$10.39	4.547%	$10.8624	$10.86	$10.85	$10.90
Purchase #3	$86.55	12.360%	$97.2476	$97.25	$97.25	$97.20
Purchase #4	$35.72	4.436%	$37.3045	$37.30	$37.30	$37.30
Purchase #5	$63.63	3.496%	$65.8545	$65.85	$65.85	$65.90
Purchase #6	$32.52	3.305%	$33.5948	$33.59	$33.60	$33.60
Purchase #7	$26.33	4.470%	$27.507	$27.51	$27.50	$27.50
7 purchase totals =	$410.44		$433.4293	$433.42	$433.40	$433.50