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	$165.51	9.680%	$181.5314	$181.53	$181.55	$181.50
Purchase #2	$5.57	4.425%	$5.8165	$5.82	$5.80	$5.80
Purchase #3	$61.73	6.750%	$65.8968	$65.90	$65.90	$65.90
Purchase #4	$240.41	10.355%	$265.3045	$265.30	$265.30	$265.30
Purchase #5	$55.88	7.656%	$60.1582	$60.16	$60.15	$60.20
Purchase #6	$245.34	7.405%	$263.5074	$263.51	$263.50	$263.50
Purchase #7	$168.75	13.145%	$190.9322	$190.93	$190.95	$190.90
7 purchase totals =	$943.19		$1,033.1470	$1,033.15	$1,033.15	$1,033.10