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	$95.72	10.720%	$105.9812	$105.98	$106.00	$106.00
Purchase #2	$85.79	3.494%	$88.7875	$88.79	$88.80	$88.80
Purchase #3	$204.78	8.675%	$222.5447	$222.54	$222.55	$222.50
Purchase #4	$154.30	13.335%	$174.8759	$174.88	$174.90	$174.90
Purchase #5	$71.88	10.868%	$79.6919	$79.69	$79.70	$79.70
Purchase #6	$162.63	11.594%	$181.4853	$181.49	$181.50	$181.50
Purchase #7	$141.92	10.500%	$156.8216	$156.82	$156.80	$156.80
7 purchase totals =	$917.02		$1,010.1881	$1,010.19	$1,010.25	$1,010.20