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	$126.65	11.337%	$141.0083	$141.01	$141.00	$141.00
Purchase #2	$131.82	7.170%	$141.2715	$141.27	$141.25	$141.30
Purchase #3	$31.62	5.759%	$33.441	$33.44	$33.45	$33.40
Purchase #4	$35.47	5.155%	$37.2985	$37.30	$37.30	$37.30
Purchase #5	$225.92	7.498%	$242.8595	$242.86	$242.85	$242.90
Purchase #6	$127.90	13.861%	$145.6282	$145.63	$145.65	$145.60
Purchase #7	$172.50	6.801%	$184.2317	$184.23	$184.25	$184.20
7 purchase totals =	$851.88		$925.7387	$925.74	$925.75	$925.70