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	$117.59	10.266%	$129.6618	$129.66	$129.65	$129.70
Purchase #2	$83.68	9.351%	$91.5049	$91.50	$91.50	$91.50
Purchase #3	$167.27	4.344%	$174.5362	$174.54	$174.55	$174.50
Purchase #4	$91.88	9.304%	$100.4285	$100.43	$100.45	$100.40
Purchase #5	$224.59	4.385%	$234.4383	$234.44	$234.45	$234.40
Purchase #6	$233.64	9.447%	$255.712	$255.71	$255.70	$255.70
Purchase #7	$246.26	9.533%	$269.736	$269.74	$269.75	$269.70
7 purchase totals =	$1,164.91		$1,256.0177	$1,256.02	$1,256.05	$1,255.90