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	$108.55	3.146%	$111.965	$111.97	$111.95	$112.00
Purchase #2	$46.65	13.510%	$52.9524	$52.95	$52.95	$53.00
Purchase #3	$243.35	8.298%	$263.5432	$263.54	$263.55	$263.50
Purchase #4	$173.73	4.295%	$181.1917	$181.19	$181.20	$181.20
Purchase #5	$135.95	4.801%	$142.477	$142.48	$142.50	$142.50
Purchase #6	$71.55	3.270%	$73.8897	$73.89	$73.90	$73.90
Purchase #7	$165.74	8.516%	$179.8544	$179.85	$179.85	$179.90
7 purchase totals =	$945.52		$1,005.8734	$1,005.87	$1,005.90	$1,006.00