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	$99.94	9.741%	$109.6752	$109.68	$109.70	$109.70
Purchase #2	$144.58	5.605%	$152.6837	$152.68	$152.70	$152.70
Purchase #3	$34.87	3.295%	$36.019	$36.02	$36.00	$36.00
Purchase #4	$153.48	10.687%	$169.8824	$169.88	$169.90	$169.90
Purchase #5	$49.40	10.384%	$54.5297	$54.53	$54.55	$54.50
Purchase #6	$70.68	3.165%	$72.917	$72.92	$72.90	$72.90
Purchase #7	$144.38	10.501%	$159.5413	$159.54	$159.55	$159.50
7 purchase totals =	$697.33		$755.2483	$755.25	$755.30	$755.20