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	$247.85	8.236%	$268.2629	$268.26	$268.25	$268.30
Purchase #2	$82.42	4.530%	$86.1536	$86.15	$86.15	$86.20
Purchase #3	$161.89	3.470%	$167.5076	$167.51	$167.50	$167.50
Purchase #4	$138.46	9.781%	$152.0028	$152.00	$152.00	$152.00
Purchase #5	$151.50	4.598%	$158.466	$158.47	$158.45	$158.50
Purchase #6	$211.90	4.140%	$220.6727	$220.67	$220.65	$220.70
Purchase #7	$38.38	6.226%	$40.7695	$40.77	$40.75	$40.80
7 purchase totals =	$1,032.40		$1,093.8351	$1,093.83	$1,093.75	$1,094.00