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	$191.88	8.795%	$208.7558	$208.76	$208.75	$208.80
Purchase #2	$98.91	10.221%	$109.0196	$109.02	$109.00	$109.00
Purchase #3	$22.50	13.736%	$25.5906	$25.59	$25.60	$25.60
Purchase #4	$241.32	13.308%	$273.4349	$273.43	$273.45	$273.40
Purchase #5	$166.34	9.688%	$182.455	$182.46	$182.45	$182.50
Purchase #6	$108.73	3.124%	$112.1267	$112.13	$112.15	$112.10
Purchase #7	$233.49	13.187%	$264.2803	$264.28	$264.30	$264.30
7 purchase totals =	$1,063.17		$1,175.6629	$1,175.67	$1,175.70	$1,175.70