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	$194.34	8.848%	$211.5352	$211.54	$211.55	$211.50
Purchase #2	$246.40	12.816%	$277.9786	$277.98	$278.00	$278.00
Purchase #3	$170.27	10.722%	$188.5263	$188.53	$188.55	$188.50
Purchase #4	$78.81	4.604%	$82.4384	$82.44	$82.45	$82.40
Purchase #5	$5.27	11.753%	$5.8894	$5.89	$5.90	$5.90
Purchase #6	$24.70	11.369%	$27.5081	$27.51	$27.50	$27.50
Purchase #7	$201.83	10.158%	$222.3319	$222.33	$222.35	$222.30
7 purchase totals =	$921.62		$1,016.2079	$1,016.22	$1,016.30	$1,016.10