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	$137.77	5.643%	$145.5444	$145.54	$145.55	$145.50
Purchase #2	$90.56	7.622%	$97.4625	$97.46	$97.45	$97.50
Purchase #3	$170.51	7.287%	$182.9351	$182.94	$182.95	$182.90
Purchase #4	$184.89	13.495%	$209.8409	$209.84	$209.85	$209.80
Purchase #5	$152.66	6.492%	$162.5707	$162.57	$162.55	$162.60
Purchase #6	$146.41	3.829%	$152.016	$152.02	$152.00	$152.00
Purchase #7	$58.79	3.741%	$60.9893	$60.99	$61.00	$61.00
7 purchase totals =	$941.59		$1,011.3589	$1,011.36	$1,011.35	$1,011.30