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	$190.55	3.448%	$197.1202	$197.12	$197.10	$197.10
Purchase #2	$136.56	4.464%	$142.656	$142.66	$142.65	$142.70
Purchase #3	$37.87	13.756%	$43.0794	$43.08	$43.10	$43.10
Purchase #4	$238.45	4.330%	$248.7749	$248.77	$248.75	$248.80
Purchase #5	$188.59	5.155%	$198.3118	$198.31	$198.30	$198.30
Purchase #6	$174.39	8.728%	$189.6108	$189.61	$189.60	$189.60
Purchase #7	$146.35	4.454%	$152.8684	$152.87	$152.85	$152.90
7 purchase totals =	$1,112.76		$1,172.4215	$1,172.42	$1,172.35	$1,172.50