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	$141.85	7.466%	$152.4405	$152.44	$152.45	$152.40
Purchase #2	$55.25	4.307%	$57.6296	$57.63	$57.65	$57.60
Purchase #3	$215.40	9.521%	$235.9082	$235.91	$235.90	$235.90
Purchase #4	$175.67	12.731%	$198.0345	$198.03	$198.05	$198.00
Purchase #5	$239.40	6.443%	$254.8245	$254.82	$254.80	$254.80
Purchase #6	$60.56	11.368%	$67.4445	$67.44	$67.45	$67.40
Purchase #7	$134.28	8.767%	$146.0523	$146.05	$146.05	$146.10
7 purchase totals =	$1,022.41		$1,112.3341	$1,112.32	$1,112.35	$1,112.20