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	$151.34	3.692%	$156.9275	$156.93	$156.95	$156.90
Purchase #2	$242.43	3.651%	$251.2811	$251.28	$251.30	$251.30
Purchase #3	$19.64	3.411%	$20.3099	$20.31	$20.30	$20.30
Purchase #4	$156.85	3.689%	$162.6362	$162.64	$162.65	$162.60
Purchase #5	$79.37	9.347%	$86.7887	$86.79	$86.80	$86.80
Purchase #6	$145.50	13.112%	$164.578	$164.58	$164.60	$164.60
Purchase #7	$227.46	13.663%	$258.5379	$258.54	$258.55	$258.50
7 purchase totals =	$1,022.59		$1,101.0593	$1,101.07	$1,101.15	$1,101.00