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	$69.44	5.564%	$73.3036	$73.30	$73.30	$73.30
Purchase #2	$31.90	5.634%	$33.6972	$33.70	$33.70	$33.70
Purchase #3	$82.80	10.462%	$91.4625	$91.46	$91.45	$91.50
Purchase #4	$245.96	11.666%	$274.6537	$274.65	$274.65	$274.70
Purchase #5	$186.59	5.519%	$196.8879	$196.89	$196.90	$196.90
Purchase #6	$225.73	9.740%	$247.7161	$247.72	$247.70	$247.70
Purchase #7	$185.65	12.309%	$208.5017	$208.50	$208.50	$208.50
7 purchase totals =	$1,028.07		$1,126.2227	$1,126.22	$1,126.20	$1,126.30