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	$245.29	8.138%	$265.2517	$265.25	$265.25	$265.30
Purchase #2	$7.35	7.407%	$7.8944	$7.89	$7.90	$7.90
Purchase #3	$149.85	6.637%	$159.7955	$159.80	$159.80	$159.80
Purchase #4	$39.28	6.766%	$41.9377	$41.94	$41.95	$41.90
Purchase #5	$88.30	4.824%	$92.5596	$92.56	$92.55	$92.60
Purchase #6	$234.74	4.183%	$244.5592	$244.56	$244.55	$244.60
Purchase #7	$244.46	6.319%	$259.9074	$259.91	$259.90	$259.90
7 purchase totals =	$1,009.27		$1,071.9055	$1,071.91	$1,071.90	$1,072.00