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	$187.76	3.339%	$194.0293	$194.03	$194.05	$194.00
Purchase #2	$139.38	7.354%	$149.63	$149.63	$149.65	$149.60
Purchase #3	$104.52	4.436%	$109.1565	$109.16	$109.15	$109.20
Purchase #4	$72.33	7.700%	$77.8994	$77.90	$77.90	$77.90
Purchase #5	$38.34	13.272%	$43.4285	$43.43	$43.45	$43.40
Purchase #6	$111.28	11.351%	$123.9114	$123.91	$123.90	$123.90
Purchase #7	$206.63	4.657%	$216.2528	$216.25	$216.25	$216.30
7 purchase totals =	$860.24		$914.3079	$914.31	$914.35	$914.30